And it is in many countries, but for some reason the U.S. doesn't seem to work that way. I was a bit surprised when my son spent a year in high school in the U.S. and I found out how youth football (soccer) system works there. Over here in Europe, we have a plethora of local clubs that collect the young and old to train and play, and to work together to organise everything, fund it, and so on. In the U.S. the football (again, soccer) seems to be predominantly organised by schools, and a very small part of players belong to actual soccer clubs. I understand the same is true with other sports (American football, baseball, basketball, etc). Similarly we have lots of clubs that arrange things like music and orchestra trainings for youth, whereas in the U.S. this is also organized around schools.

This is good in many ways - for instance, the integration of activities to the school day helps it for kids - but at the same time, it makes the school's "quality" (in terms of what the teachers and staff are like and what kind of parents the children have) all so important. If the school fails, then everything will. And if you don't have kids at school, can you really contribute to the community in the same way as a seasoned football veteran can in a local club?