I had an awesome professor once who intentionally assigned the old editions of every book needed for the class to save us all a few bucks. If I recall correctly, she called the publisher out on shifting chapters for the whole class to hear.

Another prof photocopied chapters of his own book to save us from the inflated price gouging of academia. He cared more about spreading his message than making money.

Two other profs only assigned historical public domain editions of philosophical texts to keep our costs down, or eliminate them entirely.

Props to all these great profs. I'll never forget the things they taught me, and one even became a thesis advisor of mine years later.

My favorite is when the chapters are the same...but the questions in the chapters have been moved / altered.

I had a prof that wrote her own book for class and the only changes one year to the next were the in book questions. Which of course she assigned to be handed in. If you didn't do her book work which was 40% of the grade.. you'd fail her class.

She was a delight. /s