I think half the problem is that the expectation of kids playing on certain teams "or else" is implicit. Maybe I'm wrong, and tell me if I am, but are coaches outright telling kids/parents that if they don't play on X team then they won't see playing time on the school team?
It's hard to attack something deniable. That just turns into he said/she said, with the coach claiming that Y kid doesn't play because he's/she's not as good as the player on the coach's club team. | 
