Also, from what I hear hockey is also extremely expensive. I've heard that you can't leave a sporting goods store without spending at least $1,000 on gear alone for a season. I've yet to hear anyone complain that hockey is pay to play.
I think the other commenter has it right, most kids just gravitate towards American Football, Baseball, or Basketball.
And in the state I live in, of probably the top five soccer teams, one is a private school, the rest are public.
Edit: I don't know if other sports are like this but so many soccer parents are just extremely unrealistic/toxic. So many think they have the next superstar, questioning the coach on their child's play time, whey their kids didn't get placed on higher leveled teams, questioning why a coach is running practices certain ways.