The pressure in Asia builds even before pre-school where toddlers have lessons to attend, to get into a decent pre-school.
Anecdotal evidence to see some 5 year kids playing in playground alone in Asia doesn't prove the point that parents in Asia are not robbing their kids of their childhood.
USA is big multi-cultural place with many different parenting styles. Painting all of them with broad brush without statistical significant studies is not ok.
One might not get arrested in Japan, does not prove anything. I might not agree completely with USA system, but it must have a reason to exist.