I suspect that it has to do with a greater sense of national identity. You come to the United States and become American. You go to any nation in Europe and remain a foreigner. Even if you were born there, if your parents are from elsewhere.
Foreigners that come here are owners. Foreigners in the UK are renters.
I think that has a lot to do with it. I met a Chinese woman married to a German. She said she wanted to stay in the States because here she could be an American and not a Chinese person in Germany. She felt that she would never be considered German and would always be looked at differently, no matter how long she lived over there and despite being married to a German, whereas here she could blend in.