In the US a minimal welfare system, semi-religious adherence to civil rights and informal networks of privilege make high immigration rates work out okay. The three solve the problems of citizens being upset by newcomers taking up more services than they return in taxes, ethnic conflicts exploding out of government unfairness, and the skilled labor to capital exchange ratio shifting too far in favor of capital for the middle class to accept. It is not a utopia but it can handle the massive immigration that built it.