I teach in college, and I see this attitude every fucking day.
I have students who will tell me that they already know the subject, that this class isn't giving them anything (entry-level/mid level English), and that they shouldn't have to take it at all. Throughout the course of the semester, almost every student will tell me this.
In the 6 sections I teach, of ~30 students, I would say 2 actually don't need this class. A VAST majority just see stuff like what you say spouted constantly on-line and by there ignorant ass friends. A VAST majority simply over-value their skills and abilities.
I'm not saying that you aren't different, I'm just saying that in a majority of cases where 'the student knows the subject already' it really is 'the student believes that s/he knows the subject already, but really doesn't know his/her ass from a hole in the ground, but because s/he is such an entitled, self-important precious little snowflake, s/he can't make wise decisions'. Believe me when I tell you this - in most cases where the student is acting out because "he is bored with the coursework," in all actuality, "he just has piss-poor self-control and his parents don't hold him accountable." The little geniuses that parents see are really just average kids who are supremely lazy in most cases. (Keep in mind that I acted out in school because I was an advanced learner, they do exist, just not as often as you would be led to believe by parents.)
Somewhere along the way, the attitude in college shifted from the very collegiate ---I'm here to learn--- to the very secondary school ---you have to teach me, good luck---. What you see with this - where instructors can track the number of pages read, is just the simplest form of teacher-student coercion to do actual God Damned work that happens every day in various forms.