[AnimalMuppet]

Textbooks are not particularly regulated, but they are an interesting monopoly. You probably don't think of them as a monopoly, but they are. If you just want to learn calculus, any text will do, but if you are taking a college class, you have to have the text the instructor says. You'd better even have the same edition. So the publisher can charge pretty much any price, because you (the buyer) have no choice.

[douche]

More often than not, you have to have the text the professor (and or department head) had a hand in writing/editing/producing, and therefore gets royalties from. It's corrupt as all hell.

[eru]

What's the actual punishment in practice, if you just buy a different textbook (or even just a different version)?

They are not gonna ask you 'What's the third letter on the second line of page 317?' are they?

[jsprogrammer]

Sounds similar to the monopoly on SIM chips by cell service providers.

We were not always required to have the same (or any) textbook in some of my college classes. Sometimes, multiple alternatives (with brief reviews) were given.