[belorn]

> We could compare that to the situation in Spain where there is a group of illegal migrant workers who are exploited as cheap work force

The term we should be using here is human trafficking. It is a extremely common practice in construction and farming. As a police officer said here in Sweden in a news article, if they went to a single major construction site the yearly budget for human trafficking violations would be used up for that site alone. It is an open secret that construction sites has a tier based system for workers, where the most illegal workers (and there are different degrees to that) get the most dangerous assignments, least amount of safety equipment, longest hours, and with the lowest pay.

A lot of the calculation on the cost of reduced immigration get based on the resulting increase in costs to construction and farming. It is quite insane how much of the economy is based on exploiting people.