Somebody would have to drive the buses and wait the tables. You're making it appear as if immigrants appeared out of thin air to occupy a social position. But the receiving country needs them, because their population is too old, too lazy, too greedy, or all three.

It's very useful to have a disenfranchised underclass of immigrants to keep your own working class in check. Bonus points if you convince the latter that the source of all evil is the former.

101 capitalism, and it has worked with you.