I'm French, my wife is Japanese. We have experience of both immigration procedure. Let me tell you that Japan's xenophobism is a myth that dates from WWII. France is far more tough for foreigners.

It is true that they are basically more uniform culturally and probably genetically and religiously than US. But you missed an important point : I did not compare US's healthcare to Japan's. I compared US' best county to Japan's average. That makes the uniformity of the country quite irrelevant, don't you think ?

2. You exaggerate the differences. 96% of Americans speak English. 87% as their primary language. Of course institutions are limited ! That's how it works in a democracy ! I agree that states are different, have some freedom (but probably not much more than a German Land or a Swiss canton, these are federal countries too) but my point is that stating that these differences are as big as the ones between EU countries is ridiculous.