>> if you don't accept a countries values, you should not be allowed to move there
But in the positive version, I think in America it is much easier to integrate if you do accept American values than it is in some European countries. And this is because, as you alluded, the only thing that makes America a unified country is a social agreement to certain shared values like rule of law, property rights, freedom to conduct business, freedom of religion, and more recently civil rights. Whereas those ideals are only recently tacked on to (most) European nations, and are not core to their identity; one can accept all those values and still never become German, for instance. Even France where many of those values originated has an ethnic nationalist core which denies integration to those who are not ethnically French. So what I mean is, accepting values in Europe is a start, but it is not enough.
And what we see in ghettoized cultures around the world, from African Americans to Algerians in France, is that the ghetto creates its own logic of rejecting the norms of the society which has rejected it. Welfare is not a substitute for a path toward individual success and acceptance in society; this is perhaps Europe's greatest mistake. On welfare, in the suburbs, who will believe and not mock the supposed values of equality and fraternity? It becomes a generational problem.