This is also, in similar theme to my other comment, because high schools aren't standardized and have often wildly different curricula, even between high-qualit

This is also, in similar theme to my other comment, because high schools aren't standardized and have often wildly different curricula, even between high-quality high schools. Colleges do a ton of work to smooth this out, from offering high-school courses for freshmen to re-normalizing GPAs to account for different grading scales between schools.