Re #25
Yes, AP courses are high school courses, but some of them do cover college frosh level material so that an advanced student can take advanced placement in college to avoid wasting time and tuition repeating what s/he already knows. Instead, s/he can learn more from additional free electives chosen from the college’s offerings.
Of course, elite high schools may have better than AP courses. But most high schools are not elite, so AP courses are the most advanced and rigorous ones they offer, and many would not be offered at all without the AP branding. It is kind of a sad state of affairs that it takes an AP branding to get worthwhile courses into high school offerings, even if the material of some more recent ones is not really college frosh level (e.g. human geography).