The U.S. Taxpayers, that's who!
Your post is just another call for business profits to remain privatized, while the costs of their cheap labor force are socialized.
Sorry, no sale.
Next.
The U.S. Taxpayers, that's who!
For example, mandate that jobs paying over $6/hour must also pay $x into a private retirement fund, but jobs paying less don't pay, and you don't get the retirement benefit either.
For medical benefits, it's not as easy, as you realize. There's always the emergency room. There what I'm saying is first reduce the substantial advantage that illegal immigrants currently have for low paying (below minimum) jobs, then the enforcement that everyone else on this thread is advocating will have a decent chance.
As we learned during prohibition, enforcement doesn't work if it is swimming upstream against a strong capitalist current.
The current laws make a legal employee cost a minimum of perhaps $8 or $10 dollars per hour, compared to perhaps $2 or $3 for an illegal. This is way too strong a capitalist stream to swim against.
Get that difference down to something reasonable, and then a sensible level of enforcement can actually close the gap, so that reasonable self interested employees are left saying "sure, I could hire an illegal for a dollar or two less, but by the time I account for the risk of being caught, the illegal actually costs me more."