The US is different, of course. People like it here once they've arrived. I can't say why, nor do I buy the stereotype that US culture is more open or individualistic. But the US arguable needs laws quota-based and micro-managey, since they are managing a huge amount of people from more diverse backgrounds. Japan is managing fewer potential immigrants and guests, and most of their immigrants are geographically close to Japan.
Despite the immigration laws being easier to grok and less authoritarian on paper, Japan is pretty strict in its enforcement of those laws. Put all I've said together and I don't know if one country is more reactionary than the other, but I think both countries are moving toward a more balanced, less eccentric immigration system at the moment.
(why you should listen to me: I'm an American and lived in Japan for four years and had to go through the process of getting my wife a spouse visa 2 years into my stay. I dealt with immigration a few times. I went to many different cities and vacations and such, and talked to people that don't speak English and don't have a passport, so I have a representative sample set.)