How is that a "kickback from the publishers for forcing these (always crap) textbooks on their students" ?

I'm not denying that black sheep exist, I am denying a pervasive conspiracy of "big textbook" to the benefit of the professors.

Also, an easy solution to not everyone buying Kinko-printed spiral bound lecture notes easily comes to mind...

I see the downvotes, but I still don't see how some guy self-publishing and printing his own book at Kinkos is proof for a conspiracy in which publishers collude with professors to force students to buy books from that publisher. If anything, it's an example for the exact opposite.