I've read lots of Zizek as a high schooler. This doesn't even come close to how dense some of his writing can be, I'm sitting here drunk on a few beers and it was a simple read. I think lots of people are actually illiterate.
(People [sorry, no citation] are saying this study is bad and invalid, but I think maybe English majors should be able to manage a bit better than that, even if it is Bleak House, and even if they were blindsided with it, and especially if they plan to become English teachers. So I still get at least some qualitative value out of it myself.)