[crazygringo]

I think one important cultural thing is that, in the US, schools really are the center of your social life, including after-school sports, clubs, etc.

There are other countries where school is just school (more like a job), where there are no sports/clubs/etc., and your social life revolves more around your family and long-term friends. Sports might come from totally separate organizations. In this case, school is much less of a social thing. So maybe that has something to do with it.