Well I don't know why they get into college necessarily, but they graduate high school because they're doing away with high expectations at some schools. In a nearby school district, students aren't given zeros. Ever. If they don't turn something in, it's 50%, and they can turn in an assignment for an unpenalized grade at any point, and the teacher still has to grade it. I wouldn't be surprised if those students pulled something like what you see in class. They get used to such ridiculous leniency, and are shocked then when the "real world" or college isn't like that. I teach AP Psych and I make it as college-like as possible. I would kick one my students' behinds if they did something like what you described. No wonder people look at us and think we're worthless.
As for ridiculous things that students say, I get the "Do I have to know this for the test?" question all the time. "Nope, I'm just up here for my health talking about stuff that has no importance whatsoever."
One of my favorites is when students have to be gone and when they come back and say "Did you do anything while I was gone?" "Nope, we each just rolled up into the fetal position and counted the minutes until you'd be back so we could resume learning."