Yeah, but it seems like some nations are only willing to invest a low amount of effort in it working out. I.e. if you're highly educated skilled worker who will integrate on their own, great. If you're a manual laborer who will do the work no one wants, for less money, pay tax and integrate their kids, great. But if the host society needs to invest in their education, social programs and integration, then screw it, let them ghettoise and hope the resulting jump in nationalism and animosity towards them will balance things out.