I think every school is different, and it may vary by department/language as well. To be clear, my DD didn’t get any credit, she was exempted from taking a language (ie, met their requirements for graduation). This also grated her access to upper level language classes, but I think a placement exam would have done the same. But again, our only experience is with this one college, the language was German (one needed a 5, I believe).
I believe one of the reasons there were so many placement tests is that there is a huge variability with the HS preparation kids arrive with, even when they have super high GPAs and test scores. Not all kids have access to high level classes, and even when they do, not all kids take advantage of that, or feel comfortable with how they did in those classes. And some kids prefer to “re-take” classes they took in HS anyway, to boost GPA (though thankfully DD has not seen much of that).
DD was surprised at how many kids she’s met who had not taken calculus, for example. And some kids, despite taking foreign language through HS, were unable to gain an exemption and have to take more coursework to fulfill that requirement. Certainly the athletes from our HS who attend elite colleges are not taking AP coursework, or at least not as much of it- they probably don’t have time, for one thing. This is also true of kids from disadvantaged backgrounds. It doesn’t mean they are not smart kids, but they have not had the same preparation, for the most part. Even in the required freshman seminars there were two levels, one of which was intended to provide more intensive writing support.
