What are the statistics on this? There are about 500k professors in the US, and they make up about 1/3 of college teachers. Also, most academics would object to this situation, so it's not apparently OK. There's a growing movement towards open-sourcing textbooks or replacing them with other kinds of online materials.

Don't get me wrong, I think that college education is due for reform.

There are examples of finding better ways to do it. My son's textbook costs were very low. The regional state university that he attended had some kind of thing where you rented your textbooks and turned them back in, often with a nominal or zero fee.

One professor at my poorly subsidized state uni who had a book he required for class was $180 or so. He had enough (spiral bound Xeroxed) copies in the library for everyone to borrow for the semester. Or you could buy a shiny new one from the bookstore or online at full fare. Another gave the classes copies of the chapters.

Yes, but this is intentional, and that's what's out of line. The main content stays the same but exercises and case studies are rotated out to force an upgrade.

The business strategy class I took in college in Ireland used the same book for two or three years, even though the book was reshuffled every year, just to enable some spreading of the financial burden on students.

At least in some fields, advanced courses are the most likely to have lower cost textbooks. Real analysis textbooks are usually cheaper than calculus textbooks. It's the introductory courses that tend to have $200 behemoths attached to online homework platforms optimized for ease of grading rather than student learning.

I love Anna but it's also a poor school that doesn't have its own library that has at least a few copies of every textbook used by classes + inter-library loans. Can be a nice way to make friends by sharing a physical book to study and do exercises from in a shared workspace.