I lived in N.CA from '74 to '04 and there was a law that prohibited you from hiring them if the work exceeded a dollar amount and you were supposed to hire a licensed contractor. I forget that dollar amount and the subsequent fine if you were caught but as I recall the fine was less than the money you'd save by hiring several Mexicans to lay brick or tile, do cement work, yard work, etc. Some were likely green card, some born here, but many were likely illegal. It didn't appear to be an issue with those that had work for them to do....and most of then did very good work.
As I recall the licensed contractors lobbied the CA legislature to enact the law but like all laws it has no teeth if not enforced. I also don't recall LEO doing much to roust the dozen or so that would be standing around the Home Depot entrance driveway.
They likely had bigger issues to deal with at the time and I can understand that....like actual robberies, carjacking, rapes and murders.
I worked for a cable company in my late teens/early twenties, believe it or not, I was made foreman, driving a van around with about a dozen Mexicans digging trenches to bury underground coax cable. On our first dig at lunch time, several came to me handing me money, I pushed back the money, apparently the foreman(s) before me were extorting money from these guys. No one ever told me they were Illegals but none spoke English and I would see different workers a lot and I was the only Dig Crew.
Anyway, they worked Hard, very Hard...no standing around. I have found this to be the case over the many years I have worked with them, around them in various jobs...
Have to share, I was not one to point them to a dig area and sit in the Van, I was young, had energy, anyway, I challenged one about my age to a Dig-Off
Not only did he dig twice as far as me, he also dug twice as deep too, lol
What was sad is several would skip lunch, not having brought their own lunch like others, I often would go buy their lunch. This was the early 80s, if Immigration was a problem, I did not know about...