Parents intimately involved in their kids level of play (vs the clubs or teams defining) is the rub with American Youth Soccer + actually any youth sport in the US.I think you are correct. Flight 1 team appears to be more even. Flight 2 & 3 teams that I saw have players with mixed skill level.
My expectation is for a coach or club to only form a team that consists of everyone at the same level but I guess it is easier said than implemented. It surprises me that it really up to the parents to decide which team to join (I understand it is an exaggeration but in reality there is a chance the best flight 3 player can be better than the worst flight 2 player).
I know of multiple situations where parents have just given up on playing the social games needed sometimes to get on or play with XYZ club. If you're new to the situation what you don't see is that there's all kinds of ways exploit the situation. Coaches, Parents, and Clubs are all doing it at the same time. This is why we as a nation can't field a good national team on the mens side. Focus is 60% playing and 40% everything else that goes along with getting on XYZ team to get noticed. In other countries parent influence doesn't exist. Players get thrown into the club meat grinder + talent rises to the top.