I also don't really get it, never saw one in my life here in central Europe, but they seem to be pretty standard in the US.

In theory a tap is easier to replace, every time I've gone to replace a faucet I'll be damned if I didn't spend at least twice as long as I thought I would contorted under the sink at an odd angle muttering curses to myself.

Big game changer for me with faucets was when it dawned on me that those shitty plastic nuts that like 90% of all faucets are held on by that are next to impossible to get a good grip on are like $2 a pop and the new faucet probably came with new ones anyway, so why the hell do I care about getting them off in one piece? I just take a chisel to them now.

Replaced a garbage disposal recently and it was pretty damn painless, I could get at everything pretty well from a comfortable seated position on the floor outside of the sink, no need to crawl under there or grope around blindly. The old one actually went on me about an hour before I was hosting a party. I was expecting it to be a pain in the ass, my usual DIY buddy was at my party and I gave him a heads-up that I might be hitting him up the next day if I needed a hand. After everyone left at the end of the night I watched a couple of YouTube videos, then pulled out the old garbage disposal, took me maybe about 20 minutes. Went to bed, woke up and ran to the hardware store the next morning and had the new one installed by noon and didn't need to hit up my friend for help. Probably would have had it installed by about 10 or 11 but I had to make a second trip to the hardware store because my disposal is hard-wired and I needed to run out for a cable connector because the new one didn't come with one (would have reused themone from the old one, but it didn't have the nut, the old disposal was actually threaded for the cable connector and the new one wasn't.

I haven't replaced a whole toilet yet (although I've taken them apart and replaced all of the internals and installed bidets) but really you just turn off and disconnect the water, undo a couple bolts, and then you pretty much just pick them up. They're a bit heavy and awkward, but there's not much to it otherwise, it almost seems like it's too simple to actually work but it does.

There's really only about 4 reasons to replace your whole toilet.

1. You don't like how your toilet looks and want to get a prettier one.

2. Your toilet is physically cracked and broken, like if someone flushed a cherry bomb or took a hammer to it or something.

3. You have an old toilet and want one that's more water efficient (and even then there may be a couple option you can use to work around it, like installing a dual flush valve, or sticking a brick or something in the tank to displace some of the water and see if it still flushes well enough)

4. Something else broke in your toilet and you have some weird, non-standard toilet that you absolutely cannot get parts for. For probably 90% of the toilets out there you can use whatever the hardware store carries that says it's a universal fit and for most of the other 10% you can use one of the two things that are right there next to it on the shelf.

Other than than those reasons, you can go buy a kit to replace basically all of your toilets internal parts for like $25-$30 that will fix basically any other issue your likely having, for another $20-$30 you can replace the wax ring and flange if that's what's causing your issue, and that will account for about 99% of any issues you're ever likely to have with your throne, and all you'll need to do it is a screwdriver and a crescent wrench (and maybe some WD-40 or your penetrating oil of choice if you have some rusted up bolts)

In case anyone feels emboldened to fix their own toilet after reading that, for a few extra bucks you can upgrade to a dual flush valve that will fit most toilets and help you save a little water, and while you have everything apart anyway go ahead and install a bidet.