In American schools, the levels of a class on, say, European History would be:
European History -> Honors European History -> AP Euro History
You would just take one of them based on your ability and/or interest in the subject.
Students can complete AP courses and, depending on how they score on the exams, earn actual college credit at whatever school they end up at.
I took the AP Physics C MITx course on edx (when I was in high school) and it was way below the level of our college Physics 1 course (electrical engineering, European university). Not saying it wasn't a great course (much better than anything my high school offered), but it just wasn't as mathematically rigorous.
Are introductory college classes in the US really so basic?
The key difference between the two systems is that far fewer people (rough guess is like 1/3 to 1/2 of kids) graduate from academic high school in those countries.
Take a look at the basic admissions requirements for Swiss universities (this happens to be the one I could find the most easily). Most of the Swiss universities listed in this table require either 5 AP tests or 2 years of college for students from the US to be considered. https://www.swissuniversities.ch/en/services/admission-to-un...
A basic US high school diploma is garbage not worth the paper it's printed on -- there isn't any sort of national standard, and the state school leaving exams just test basic literacy.
One of the criticisms of US public education is that too large of a fraction of the curriculum is spent "teaching to the test", which doesn't allow room for teachers to show their individual talents and design curriculum which really reaches the students. I fear that additional national standards would only worsen that trend.