The real barriers to foreigners coming to the US are all bureaucratic.
Should I take this in the natural way that a native speaker of English would take it, to mean that you have never personally been to rural America? Where else have you been, and what other countries' attitudes toward immigrants are you comparing to the United States, which has one of the highest rates of legal immigration in the world?
I should explain that I have spent much of my life in rural America (where my mother grew up, and where most of my aunts and uncles and cousins live). The rural Americans I know have been very accepting of my wife, a first-generation immigrant, and generally accepting of immigrants to the degree of often hiring immigrants as their various business ventures scale up.
I have also lived outside the United States, although only on one other continent, and in my years overseas I have met quite a few people from a variety of countries who report that their countries of course also limit immigration. Is there any country in the world today with no restrictions at all on immigration? Where is it? Who emigrates to settle there?
Sorry. But that really made me laugh out loud. Seriously. Where do you think that bureaucracy finds it's origin?