[saveliberty]

How does the employer necessarily know if the employer is presented with faked or stolen information?

Did you know that the state of California enacted regulations such that an employee has the right to change his or her name and taxpayer ID once per year? So follow how this goes— someone “borrows” a taxpayer name and ID. Maybe it’s the uncle or some other relative’s but there it is. Fine, the annual tax withholdings get reported and the employer gets dinged by the IRS that there’s an issue with that TIN. $50 fine and a demand that the employer has to go fix it. Employer goes back to the employee and says - hey there’s a problem here. Employees says, whoops, I made a mistake, here’s my new information. New name, new taxpayer ID and CA says that the employer has to take it.

That’s a far cry from the businesses that actively seek illegal aliens.

[zeugma]

Employees says, whoops, I made a mistake, here’s my new information. New name, new taxpayer ID and CA says that the employer has to take it.

Yeah, I'm sure legitimate people forget their name all the time. 

[dragnet2]

How does the employer necessarily know if the employer is presented with faked or stolen information?

The fix in and has been for a long time.