This may be a dumb question, but when you get the copy-cat book, it will cover the same topics but will have different end of chapter examples and questions which are often used for assignment purposes. How does a student navigate that? I suppose they could ask a fellow student that did fork over the dough for the actual textbook. Anyways, it's a racket. I think in 50 years people will look back at how walled off our education system was in astonishment.
I haven't visited the Boundless site, but I think it's not really as much about copy-cat books as it is about replacement reading material. If your teacher wants you to read about Hegel's theory of history in chapter eight of The Nuances of Philosophy, 13th Edition, for instance, their site has a non-copyrighted article that covers the subject, listed as a replacement for that chapter. So if you're only interested in understanding the course, you're set. The problems and questions in the textbook are a different matter. That's one of the ways publishers force teachers and students to buy the new couple-hundred-dollar books instead of the cheaper older editions. They just switch the numbers of the questions at the end of the chapters around. If a teacher cares about students getting ripped-off by publishers, they'll just create the assignments themselves, so no one has to buy the absurdly-priced new-edition textbooks. But, these teachers will usually assign non-textbook reading material in the first place.
The last time I was in school, I ended up getting three different editions of the same textbook for a class. Initially, I got the previous edition of the book, which the teacher said I couldn't use because some of the problems were different. Then I got the "international" (meaning Indian) edition of the book, which I couldn't use because the teacher said they had replaced a few of the problems with Indian-specific problems. Finally, I ended up getting the overpriced new edition. This gave me the chance to see what the differences really were between editions, though. The differences between the new and previous editions? They combined two similar chapters and replaced the last paragraph of the earlier chapter and the first paragraph of the later chapter with a single paragraph. They also re-numbered the problems at the ends of the chapters, replacing a few of them with new problems. Finally, they added a paragraph in the introduction boasting about how improved the new edition was. The difference between the international and standard editions? They re-ordered the chapters and replaced American terms with Indian terms for a few of the problems.
I wonder if part of their "justification" is that the rearranging and rewriting of the questions helps to prevent plagiarism?