> They get a plenty bad enough shake.

Then why are they coming if it's so bad?

> Other countries get by just fine not having such a huge delta between haves and have nots on citizenship, and their social cohesion is better for it.

Outside of the USA and a few other countries, there is no social cohesion at all shared between natives and immigrants/foreigners, just different levels of animosity. Even between different native ethnicities and groups.