student manages to find a PDF of the book and sends it to all of the students in the class. Professor calls in the student to chastise them and talk about the immorality of piracy. Next class period, teacher shows up and has assigned the class a different book and changed all of the required reading. What gives? Do professors get kickbacks for assigning certain textbooks? Is there an issue of immorality on the professors side by selfishly adding another absurd cost to the secondary education racket? 

I don't know why this bothers me so much... but maybe I'm looking through too narrow a lens.