In a strange kind of way, perhaps this 'fraud' by illegals, is a boon to the flagging reserves of the Social Security Trust Fund!
You know... they're (illegals are) paid with checks, from which Social Security, Medicare and IRS withholding have been deducted.
The funds are going somewhere, and they're going to the feds, and to the accounts of those whom were legitimately issued the numbers.
Kinda' weird when you think about it, ain't it?