Somebody stole my calculus textbook and sold it to the bookstore. This textbook cost over USD 200 new iirc. I would have probably paid the thief more than what the bookstore paid them for my used book.
to me it sounds like they were serving the interest of poor students by distributing cheap books to where there was demand. Otherwise those books could have been left in the bin gathering dust
They would have just thrown them in the dumpster. The point of the bin was to stop people from filling the trash cans with their used books.