It might be. At my university all material was made by the profs at the school and distributed for free. But I've heard of schools where teachers force students to buy the books they have themselves written.

My point wasn't that xeroxing books is good or bad, just that coming up with arguments against it is easy and so is for research paper piracy. Having worked for a while in research, I absolutely condone what sci-hub does and used it many times.