Japan has high population density but a small piece of land, and it is probably the most mono-cultural population of it's size in the world.
I agree that we need in America is stronger leadership. But we shouldn't be looking to the government for leadership. The government should follow the will of the people, not lead it.
Democratic governments act when they feel the people want them to act. The reason the US government didn't act early is because the majority of Americans were not yet concerned about the coronavirus until recently, and it would have been unpopular.
Japan would not have acted so strictly and so early if their culture and respect for community weren't strong. It would have been unpopular and ineffective.
What's needed for Americans to tackle these types of issues better is more trust in the community and stronger citizen leadership.