The take home salary is *not* the significant cost of hiring an American worker. You have FICA, Medicare, Unemployment insurance, Workers comp, plus lots more nickle and dime costs. Let me illustrate the end result with an example from a country even worse (in this respect - of course it is a nice place in other ways): Brazil.
Brazil got a socialist government that tried to end worker exploitation by decreeing a litany of benefits for all workers. Mandatory unemployment insurance, health care, maximum weekly hours, minimum wage, you name it. If you land a legal job in Brazil, you are really well taken care of - and you even get some spending money. The problem? Very few companies can afford to hire workers following all the rules. So instead, they offer jobs "under the table". You work for us, while officially unemployed, and we'll slip you money under the table. No benefits. No guarantees. This is what most workers in Brazil end up with. The end result is the opposite of the good intentions.
A friend was a lawyer in Brazil working for a non-profit that sued companies that failed to follow all the employment rules. The catch? His law firm hired *their* workers "under the table" with no benefits - they could not afford official workers as a non-profit.