They already did that. Don't you remember the big ICE raids on all of Swift's plants back in Dec, 2006?
They got rid of all the illegals and replaced them with these Somalis and Burmese who entered the US a "political refugees".
Oops, I’d forgotten that I read about that right at FR. I still wouldn’t trust these companies to let a few sneak back in under the radar though. Did Swift get any meaningful fines for hiring all those illegals? I don’t know.