US sports is surprisingly "socialist", with systems like drafting ensuring that a team can't just buy up all the best players, so the league stays interesting. It seems obvious that player wages are kept lower in a system like this ... But I think they do pretty OK anyway.
Amateur sports (college and high school sports) is also much, much bigger in the US than most other places.
Both these trends I would guess have to do with the US's traditional ban on sports gambling.