AP classes are a scam. Duel enrollment and CLEP exams are the way to go.
AP classes have become a scam. 40 years ago when I was in high school, I took several AP classes and did well enough on the exams to get lots of college credit and graduate early. They hardly do that anymore with AP exams now (the University of California system remains the exception)--perhaps some exemptions at best.
I am skeptical that colleges "hardly" accept AP exams for class credit nowadays. At my alma mater, the University of Maryland, I was able to use AP exams to amass three semesters' worth of credits. The chart posted by the University of Maryland for the 2021–22 school year shows that almost every AP exam was accepted for class credit. I would imagine that this is normal. What evidence do you have that it is not?
Must be a public flagship vs private elite/liberal arts school thing, or maybe a pre-health thing as well.
The above is probably correct. I was premed at Vanderbilt in the 1980s, and college credit would be generally given for AP exam scores of 3, 4, and 5. That allowed me (and others in my class) to graduate early with huge savings. That option hardly exists at Vanderbilt and other private schools today.
My daughter is now at a private university--took several AP classes in high school with scores of 3 and 4--no college credit whatsoever but rather the option to place into higher level classes in disciplines irrelevant to her major. If she had gone to UGA or the UC schools where she had been accepted, it would be a different story.