I only know of what I have been told. I work with a lot of construction workers here in Los Angeles and almost all are Hispanic. In Los Angeles you are required to pass a Contractors State test before becoming a contractor. It is not an easy test unless you have a photographic memory. Even if you understand what you are reading on plans it is often a debate as to the meaning of a note. With earthquake, wind, soil conditions and environmental concerns, building conditions are getting harder to discern.
The people I work with tell me that in Los Angeles you have to belong to the Union. You no longer need to be a licensed contractor, as an alternative you can also now show you are in the union. This is in Los Angeless mind acceptable. Never mind the fact that they dont check for legal citizenship or if you speak English or you have an education above 3rd grade.
Add to this that very few projects have Union members. No one can afford Union wages. The people that insist on Union workers are the government. Our Schools, our highways, Libraries, everything government related is Union and they dont check for legal status. This is the reason that our military bases have been hiring illegal aliens to do their work. It can be argued that by hiring Union Members you are hiring the worst of the worst.
I heard some union boss boast that it is not his responsibility to check the legal status of workers. Hey, but let them build a roof over your childs school.
The big, expensive construction jobs.
You said it.
And, you're right.