That’s a great point, @ucbalumnus , and my take is that I got a 5 on AP Calculus but was in no way ready for proper college calculus. I memorized the formulae almost solely for the duration of the exam and forgot them within minutes of turning it in. I crammed the test and got my 5, but any school that would thereby give me credit or bump me up to more advanced math would be in for a surprise.
Foreign language is another one. I got a 5 on Spanish, but haha (jaja!) I don’t know Spanish. I had a student a few years ago who crammed and got a 5 on Spanish as well, then at Bowdoin he was told he couldn’t register for intro Spanish. But he didn’t know Spanish and was absolutely not qualified for a 200-level Spanish class. He actually had to change foreign languages!
I’m sure plenty of people who do well on APs are ready for bigger and better things, but the problem is that they don’t have to be that good at a subject to get a 5 on its AP.