In high school I was often frustrated, since it was far too easy to "max out" the knowledge of my teachers, and certainly none of them were working experts in their respective fields. This never happened in university - I have never, to date, been able to get to a point where I'm thinking well ahead of the prof, or even close.
Most university lecturers are there to do research, teaching is a sideline. Some people genuinely like teaching, among them some of the research productive. But optimising for two things at once will not give as good results on either measure as optimising separately.
I don't hold out much hope here given that the main purpose of elite colleges for undergrads is status by association with prestige, which comes from the research productive. Teaching excellence is strictly a sideline.
The real problem is solving the problem, which requires changing the incentives that drive professors. At the moment, hiring and tenure decisions at virtually all universities (and all the big ones you've heard of) are made mostly on research and publication. Teaching simply doesn't count for much. Therefore, the people who succeed in getting hired and getting tenured optimize for what they're being judged on: research and publication. Teaching is secondary.
Once you've realized this incentive problem, the question becomes, "How do you change the incentives?" I have no good answers for that, but it's the real question you should be asking if you're genuinely interested.
(EDIT: And, by the way, I'm a grad student at a big public school. I get to hear about this kind of stuff all the time.)