If illegal immigration is such a problem, why not fine businesses 5x salary for using the labor, for as long as it was used? There are a lot of systems in place to verify working status at this point. It eliminates any incentive to hire this cheaper labor willing to work for lower wages. The people coming will be coming for a variety of reasons but it won't be to take the jobs of the uneducated Americans
Also, I'll keep saying it: the cruelty is the point. And sadly the Stanford experiment shows that people will always oblige over the change to torture others if there's no consequences.