This has much to do with the history of Japan and its inhabitants vs the history of the US and the type of people who moved here and occupied / colonized it (don't use "settled", there was no settling, only stealing). The US was largely built on individualism, high risk-high reward, lawlessness, aggression, and a lack of social cohesiveness (don't like it somewhere? there's plenty of other places to go and be on your own). Japan on the other hand, while it had wars/violence too, that happened within a highly structured society built on a form of feudalism.