And once it is officially known they'll have to act, so a lot of it is making it take a long time to be officially known. It isn't like they purposefully hunt

And once it is officially known they'll have to act, so a lot of it is making it take a long time to be officially known. It isn't like they purposefully hunt for those who do things illegal, they just are aggressive enough in who they give their contracts to that there is a selective pressure for those who can cut costs by hiring undocumented workers. The big companies would be just as happy, maybe even slightly happier, hiring a company only employing legal workers if they could do so for the same price.