Not true - if you make enough of a pest of yourself, particularly if you get others involved, like unions.
INS raided FedEx's under-construction new headquarters and busted over 150 illegals one day in the past two years. Here in North Carolina, they busted over 100 illegals one day who worked through three temp outfits in Winston-Salem. And email/phone your congresscritter about egregious cases; in Raleigh, an illegal dumb enough to give an interview to the local "mainstream" daily under his own name at the bodega he worked at was arrested when INS agents waving the clipping - evidently snailmailed to congresscritters - raided it.