Except that it is difficult to take a class without buying the textbook, and they are expensive. When was the the last time your professor mandated that you see a certain sports team play, but base tickets cost $100?
High fixed costs relating to an academic activity do not provide indicators to the ethics of the people who produce the required items.
Or, to put in another way, you are not mandated to attend a class where the professor will charge you to see a certain sports team play. Somewhere along the way, you made a choice that brought you to this mandate.
As a free-market type would say or as Stephen Covey would say, take responsibility for your decisions. If you don't like the mandates that come with a certain class, don't take that class.
Just because people can technically choose to avoid the situation entirely by dropping out or altering their life's course by switching majors doesn't justify ripping students off, or any other such small evils.