That will depend on each state, because in countries like mine "Colombia" we now have a problem with Venezuelan immigrants, who exacerbate the situation in several regions of our country and the state can control it because the money is holding by corrupt politics and the money of the state is highly reduced it.

For each country will be different because in Europe there are more accurate controls for these situations and the corruption is much lower than in Latin countries.

I know it's a little bit different to your whole post but i wanted to share my opinion about immigrants in general. Regards