AP = advanced placement. You take a harder version of a given subject, and if you pass an exam, you get credit for that course in college. It is really equivalent to an IB course or a British A-Level (or whatever they are calling them now?). However, high school teachers tend to overwork the students in these courses (which is why I think they are terrible college prep, even though you learn the material) so it is very difficult to take more than three or so per year. So students who are from a remotely decent school district will probably take a few of these, which comes out to being similar to doing IB courses and then going to university. A big problem in the states is that we do have degrees in areas that wouldn't normally require university degrees in Europe (Childhood development = preschool teachers, accountants, and so on). There would be less need for gen eds if one limited US universities to only serious academic majors. Having said this, learning philosophy from someone who has a doctorate and knows the material exceptionally well is probably a better experience than learning it from a high school teacher (whether in a US AP course or a more rigorous European high school).