The cost of finding ILLEGAL aliens is largely unknowable?
Ya mean the SSA won't tell ICE how much they want for the information (names, addresses, employers' names, employers' addresses) that the SSA has in its Earnings Suspense File? That will find the millions and millions working "on the books" with bogus, stolen SSN's and IRS individual ID numbers. The SSA has another file for the ones working ILLEGALLY on "no work" SSNs.
Wow, those federal agencies can be mean to each other.
If you honsestly think the Earnings Suspense file has real names in it, you’re dreaming.