I think an answer would need to look at the difference in how kids and teens play soccer in the US vs other countries.
In the US soccer is mostly a younger kids' sport, and is generally highly structured, with kids playing on teams once or twice a week. Compare to Europe, where many boys are playing once or twice every day, in an unstructured format, during recess and after school.
Starting from a young age, Europeans who show talent are getting drafted into soccer academies before they're 10, greatly increasing the amount of competitive play. But this is on top of the everyday soccer they're playing.
For a US kid, soccer is typically "pay to play." A local league costs money. A private high school with a good program costs money. In Europe, beyond (again) the continuous unstructured play, the academies and farm teams are free.
Finally, a good European player doesn't usually head to college. They may be playing for a serious club team at 17 or 18.
Meanwhile, a gifted US soccer player heads to college (maybe on a scholarship but maybe not--again, pay to play), plays for the varsity team a few times a week during the season, and four years later might get on one of the relatively few club teams.