Exactly.
Since when does a criminal get to keep the fruits of their criminal activities ?
That goes for the employers as well. They should be charged, and in addition to the fines, they should have to pay the difference in wages between legal and illegal workers.
Of course, this whole SS issue wouldn't even exist if the employer had verified the SS# really belonged to the worker in the first place.
Can an invalid SS# be used to deny or terminate employment?