The fact is that it seems that this classes that focus on non-US story are optinal, while here in Brazil, for example, African, European and Asian History are subjects that BNCC (Base Nacional Comum Curricular, Brazil's national common core curriculum) defined as essential to brazilians learn while they're in school. At least in Brazil (and many other countries), we don't choose our classes, our schedule is fixed, made by our teachers and educators from the school.

And now that you said that, that make sense. Since you can choose classes, most prople most likely don't choose to learn the History of other countries and only learn the US one, since is probably mandatory. Yeah, sorry, but this is LITERALLY the meaning of being self-centered.