Not been my experience in NYC and other places. Quite the opposite. Also have you seen European integration of foreigners up close? Middle East? Asia?
My guess is no, because these places make it far more difficult to assimilate (if not impossible)
I suspect we're disagreeing over what it means to "assimilate" or "be accepted as" one of an ethnic group. Imagine a stirring speech where a speaker says "I have dreamed of a respite from the trials our people have undergone". When the audience hears "our people", they are going to think of a certain group that they imagine themselves belonging to. In America, a miniscule fraction of the population thinks of "everyone who is legally an American" when they hear the phrase "our people".
However, some other place like Paris, the massive city-state of the white Franks, has a carefully guarded culture that they gatekeep as a majority ethnic group. You can live in France, and you can speak French, but you can't "become French" because many of the people who call themselves "French" think specifically of white Frankish/Gaulish/Roman descendents. That's just not happening in major American cities.
So, ghettos. I'm not saying there's not a "little Italy" in most American cities, but a Turkish person living in Germany their whole life is still Turkish. American in Japan, same. These places don't even allow the possibility of assimilation.
Or as my English friend put it, "there's a difference between tolerance and acceptance."