It's the bosses who take advantage of migrants to increase exploitation.
This argument is used in the debates Does being on the left necessarily mean being in favor of mass immigration? and Should we accept immigration?.
This argument is an objection to Large-scale migration signals the end of the European social model.
Summary
Quotes
“The employers of undocumented workers are sometimes small-time margoulins providing services for larger companies, in cleaning or security. But they are also big companies like KFC or Buffalo Grill, where 15% of employees were undocumented before the strike. Or the big construction companies, Vinci, Bouygues and Eiffage, who cascade subcontracting across all their sites, enabling them to hire undocumented workers while washing their hands of the consequences. They are the ones who cheat the law, but it's the workers who are punished. While 30,000 workers are deported every year for lack of a valid residence permit, fewer than 1,500 employers are charged with "offences relating to the employment of foreigners without a residence permit". When they are convicted, which is rare, they sometimes pay a fine... but they are never deported!”
