I hated this, and only encountered it once, in my Econ 102 class. We had to "buy" the online pass to view the online "textbook", which was really just a document wrapped in a flash applet, with "interactive" homeworks, that expired after 6 months. I asked the professor if he had another alternative, but he said I could always drop the class. Thankfully that was the only class I had to do that for.
Most other professors, especially within engineering were more than helpful with either giving out the ISBN so we didn't have to go through the bookstore, or in graduate school, had their own notes for the class, so a book wasn't even necessary. One class we were assigned two books that were available as PDFs from the authors, intentionally to be given away, which the professor pointed out. Thankfully in my engineering classes the professors have been helpful about allowing older editions of books or having a low cost alternative such as a compilation of notes. In my general education classes is where I've always encountered the incredibly expensive books that absolutely had to be the latest edition. I think it says something that the engineering books tended to hold up their value more than the books for those other classes, where a $130 english book ended up going back to the bookstore for $1.30. The engineering books were usually worth keeping too, once you got past the intro courses.
Oh, and the point I came here to make: Having a patent on an idea doesn't make it a good one.