I had a class where the textbook did that. I always would get last year's books to save more than a few coins, but the professor of this class would go through the problems in-class, and they were all different from what was in my book. I went to his office hours to understand why the problems he went over were different from the ones in my book, and he immediately lectured "Ahhhh you must have bought an older book from the bargain bin. I require this year's book in my class and this is how I know who failed to pay for the correct book." The professor was the author of the book, of course. It was at that point it sunk in what a huge grift higher-education was.

I forgot the professor's name, but if you're reading this, fuck you, Dr. Shithead (and all the other Shithead professors who do this).