I am sure every single person working in the French factory will be a legal resident. /sarcasm
I'll bet you $1000 right now that every one of them will be. These are not fly-by-night chicken plucking or hedge trimming jobs. All the jobs will be at well above minimum wage, and most will require an educational background and extensive on-the-job training. The aren't going to invest the time and money necessary on someone who can disapear at a moment's notice or take a chance on screwing up and having an ICE storm in their factory. This stuff is not dumbed down sweat shop work.
Now maybe some local landscaping company that hires illegals will be contracted to mow the grass outside the factory, but everyone inside will be legal.
What the hell is your problem with providing high paying jobs?