Ah, how wonderfully ignorant of you.
One of two things happen when an illegal immigrant receives compensation:
1) They do so through the utilization of a fake SS number. This means that NOT only do they pay taxes to the IRS, but as they are using a fake SS number, they will not be able to file a return and subesquently receive a tax refund.
REALITY: Due to their inability to receive a refund, when this manner is employed, illegal immigrants pay MORE in taxes.
2) The money is paid under the table. In this case, the employer is unable to write off the cost of the labour, as there is no W-9 on file.
REALITY: Due to the fact that most employers are at a higher tax rate then their labour staff, MORE tax revenue is contributed than a documented worker.