People one might call "black" make up roughly 12% of the population of the USA but just 0.5% of the population of Germany. Furthermore (and this shouldn't be surprising after centuries of repression) the black population of the USA is, statistically speaking, doing a lot worse than the rest of the country.

(Population numbers are from Wikipedia.)

Thus, from a German point of view, black people are rare individuals. From an American point of view, black people are a large, distinct subpopulation and it's easy for a person looking for a reason to reinforce his racist beliefs about them to find it.

Also (and this is is conjecture) I suspect that Germans outside the far right may be unusually reluctant to stereotype minorities, for obvious reasons. In that sense, Germany rather than the USA may be the outlier, but the problems in the USA are going to be particularly visible because the USA is such a huge presence in global culture and because the different groups in the USA are easy to distinguish while the ones in many other countries look and act the same as far as an outsider can tell.

I wonder if there have been strong efforts of American politics and society to get rid of these stereotypes and gain equality for everyone.

Of course, and stereotypes are not tolerated in many contexts. For example, I'm a white-collar worker and I'm pretty sure that I would have serious problems at every job I ever had if I said or did something racist at work (or even outside of work if it became sufficiently public).

Addressing the education portion of your question, I grew up in the American South in the 1980s-90s, and I learned plenty about the horrors of slavery and Jim Crow in school. I recognize this is a single data point, but am pretty sure these are widely taught. I also don't really hear anyone calling for a return to slavery or Jim Crow, so this education seems to have successfully imbued our culture with a sense that these are bad things.

I think your overall question is answered somewhat by the fundamental demographics of each country. What percentage of Germans today are ethnically German? A lot. In the US, our racial mix is much more fragmented, to the point where racial minorities have thriving subcultures that some people don't view as extolling "traditional American values," whatever those are. But these subcultures are increasingly visible and powerful, leading to resentment among many who view their culture, that of "traditional American values," as losing power.

The single largest ethnic group in the US are people of German descent (I'm one of them), with well over 40 million people, and these people along with people of British descent are largely the ones driving this "traditional American values" bullshit. People of Irish descent used to be subject to serious racism in the US in the early 20th century, but have since been fully accepted into the dominant white culture and many now also participate in white racism against Black and Hispanic people.

Everything is still segregated in the Southeastern USA. I can't really say how much is done because of actual direct discrimination or otherwise, but there are separate mostly black and mostly white areas in most cities.

The States of the USA are much more autonomous than it may seem from the outside. The southeastern USA is the Republican stronghold. Republicans have long acted like a criminal organization with gerrymandering that minimizes the votes of black and educated communities. If you look at the map of average credit scores of citizens in the USA, you will see the Republican regions as if looking at the political map. Republicans are toxic misers when funding government. The police in the Southeast are poorly equipped, poorly paid, and poorly trained. It is a job that attracts some of the worst kinds of people, and when they are sent into poorer areas with people that have a slightly different culture than themselves, they tend to act stupidly.

Republicans have played the long game of ignorance. Americans are poorly educated across the board, and especially in the Southeastern USA. Uneducated people are more easily manipulated into populism or by platonic sophistry. There is not a lot of social mobility in the South. I'm from Alabama originally, and live in California now. These two may as well be completely different countries. Their access to information is different, as are the culture, and opportunities for the average person. The average Californian is making over double what the average is in the Southeast. I've never been, but from what I do know, the difference between CA and the Southeast is maybe like Germany and Hungary. The base GDP numbers of CA are skewed a bit by how much rural area there is and how population is distributed. In Southern California, life in the suburbs requires around $120k per year to own a low end home and pay the bills. In the same class of suburbs in Atlanta Georgia (largest Southeastern city), you need between $60k-$75k for the same home and lifestyle. The primary driver of this cost is simply employment opportunities.

The Southeastern USA is our primary backwards ignorant backwater region where people cling to radicalized religion and are deeply conservative due to isolationist ideologies. These people hate everything unfamiliar and different both regionally and abroad. They can barely read as a skill, never read for recreation or self growth, and only ever work and watch whatever garbage is on Fox on the TV.

The African American community can be just as bad about harboring racism too. I went to a University prep highschool that was 90% black and was a special institution designed to help uplift the black community. Of course it was a largely privately funded "magnet school" because Republicans never fund such programs. I experienced many racists in school as one of the few white students. Most of my friends were black. I dated a black girl too, not that it mattered to me. It is complicated, but in general the black community is deeply traumatized. It is largely due to ongoing incompetent mismanagement. Incompetent government is good business for the ultra rich, and so they fund it, while the uneducated elements of society are not smart enough to see the big picture and vote for change.

The USA is actually a pretty shitty place for anyone of lower class. Things like immigration are harped on because it perpetuates the delusion that everyone wants to be here when that is not really the case unless you're in a hell hole like Venezuela.

Sorry, how is this a science related question?

Are you from a major metropolitan area or rural? I ask because a lot of this tends to fester in rural areas and the us has a lot of them. Its not all of it as you also get people pretty quickly blaming when their lives are not great. White people black people, black blaming white people, and citizens blaiming immegrants. Add in that the us wealth disparity is way high. Like it was in the gilded age. We are sitting at a 40 on the index while germany is a 30. Even worse we had a supreme court ruling called citizens united which effectively said money is speech and allows for unlimited money in our politics. Between rich folk wanting to push division among the poor and some foreign influences that really don't care as long as there is division and chaos as maximally as possible. Add in social media and its ability to link up people who locally would be pretty much alone in their views into a nice little confimation communities. Whelp at that point we have what we have today. Its gotten to the point actually were I can't tell how much are assholes are influencing abroad and how much abroad assholes are influencing ours. Alls I do know is the real issue is money and how unbalanced ownership of it is now. the highest is in billions so nine zeroes. So if you don't have at least 5 zeroes you should certainly should know where you stand and because of how massive the increase each zero is. 6 or 7 are still way down closer to the only zero end than the top.

Remember that Amerikkka is not a democracy, or socialist country. We are more of a oligarchy and we are ruled by the corporate elite. The system has propaganda everywhere saying we have power. But when the billionaires don't like something they can just throw money at the government (or however they do it) and it will change, Amerikkka is a capatilism country where we brainwash the people that think to believe that not having basic necessities is good for us and instead of helping each other we should fight each other over the little amount the corporate overlords give us.

There will be people who will respond saying "na huh! Not true". Propaganda in this country is EXTREME and sense all media is owned and operated by the billionaires... It's easy to brainwash the country (hence why TikTok is getting banned. Not owned by Amerikkka elites, and word of things they don't want us to know comes out from it, can't control it so ban it)

I’m totally aware that there are still many racist people and even neo Nazis in Germany

This is what you need to focus on

Have you read "Was weiße Menschen nicht über Rassismus hören wollen, aber wissen sollten" by Alice Hasters?

Please. "Vergangenheitsbewältigung" cannot be applied to racism as a whole, neither did it happen in the way that would justify a national mythos (vgl "Gegenwartsbewältigung" by Max Czollek). Please don't point fingers as a European. And German.

The difference is that, in World War 2, Germany was reduced to rubble and a significant fraction of its population was killed off because of the direction that its society took. This forced it to take a really long and hard look at itself and figure out what it could do to make sure that this never happened again.

By contrast, the U.S. has never been put in an equivalent position. The bloodiest war in our history was actually the U.S. Civil War in the 1860's over slavery (and some other things, but mostly slavery). Although the anti-slavery North in that war won and was able to successfully end slavery in the entire country, racism itself was a whole separate issue, and (simplifying the history a bit) it continued to exist formally as a less extreme government-backed institution until the mid-20th century. (An example of this were the "separate but equal" schools that segregated black children from white children and were very much not equal.)

Of course, this only changed the law of the land, not hearts and minds. Education is very local, so there is no central authority which makes decisions about these things, and people regardless have the option of sending their children to private (often religious) schools, or even to home-school them. Furthermore, unlike many countries, we take freedom of belief extremely seriously, and additionally we extend this to a near-absolute freedom for parents to teach whatever things they want to their children to believe. The U.S. stance is essentially that we might not like the values that our neighbor is teaching our children, but we like the idea of the government telling us what values we are required to teach to our children even less, and this is essentially because our country was founded on a fundamental distrust of government and this general attitude has propagated down the generations.

So, what would it take for the entire country--and remember that this is a huge and incredibly diverse country--to get together and decide that we really need to, collectively, put aside our own individual opinions of what our values should be and what we should be teaching our children and refashion our entire society around a new collectively held set of values? That is asking a lot of people, so probably the most likely way that would get done is if fascism takes over our country and drives us to start a war that results in the entire country being reduced to rubble and a significant fraction of our population being killed off. This would force us to really take a long and hard look at ourselves and figure out what we could do to make sure that this never happened again.

(Except that now that nuclear weapons exist, "rubble" takes on a new meaning, so that rebuilding part may not get a chance to happen...)

Basically: money 🤑💰. The desire for more of that led to all sorts of bullshit made-up "science" supporting the doing of what the people wanted to do anyway.

Here's a fantastic introduction video from what I consider a great series: https://youtu.be/Ajn9g5Gsv98. In particular it contrasts slavery in North vs. South America, where the latter was so much more violent and bloody and dismembered so many more people that they had to constantly import more bc so exceedingly many died that they could not keep a self sustaining population of them, which somehow still made the northern version all the more evil even while being more "gentle" bc they could therefore breed slaves like cattle.

The dehumanization might have been part of the point, or it may have only been helpful to make the money, but either way, the families of slave owners who did not go out into the fields and therefore were not as closely associated with it - though crucially, still directly benefitted from the work product - went along with it all as collaborators due to the fact that their financial status depended upon them doing exactly that.