In Europe, they do do it differently. Players turn professional at 16-18 depending on the sport and then ride the bench until their mid-20s unless they are truly prodigies. Pro teams are responsible for developing talent and have feeder clubs that field toddlers; they also support B/C/D/E-level leagues which play on town/village level.
What's happening in the US is that the educational system is subsidizing player development and regional promotion for the big pro leagues--which are such a big business it's not even funny.
"The High School Football Team" is an incredibly common movie and TV stereotype, that has no equivalent whatsoever over here, and until recently I never really thought about how completely different the situations are.
How did this happen? Why did junior sports become attached to high schools and colleges in the US when there's nothing like it in Europe?
In scotland rugby developed this way, so that now the "FP" (i.e. school) teams feature promininently in the top two tiers: GHA, Boroughmuir, Watsonians, Heriots, Dundee High, Edinburgh Academicals, Aberdeen Grammar, Stewart's Melville are all such teams.
School\Uni rugby (universities compete in a separate competition) is the closest equivalent we have, though it's utterly unable to compete in terms of attendance and money :)
What's happening in the US is that the educational system is subsidizing player development and regional promotion for the big pro leagues--which are such a big business it's not even funny.