Does that mean you go to the Home Depot parking lot when you need a plumber or an electrician? Habla espaniol? Union certification means you actually get a master plumber or master electrician. No we don't need unionized maids or dishwashers, but a union (guild) is essential for some trades.
We don't have these issues here. Are there illegals doing this type of work? Probably, but even if I needed an electrician or plumber, I'd just look in the phone book and verify the trade license of the guy or gal I hire for the work. Licensing in the trade is sufficient which nullifies the reason for a union.
Personally, I do my own electrical work, plumbing work, rough carpentry, mechanical systems, etc....always have as these are the things that any man should be able to accomplish with a bit of study and a decent manual or guide. Here, we can do the work, with a valid permit and just get it blessed by the Inspector. I've done several homes electrical work and none have burned down yet. Plumbing is no different, roofing, you name it.
My father was a journeyman tool and die maker at GM. It was pretty well known that if you earned your Journeyman card at GM, which he did, he probably wasn't qualified to work in an independent tool and die shop. He would have had to start at the bottom and learn the trade all over again. Mediocrity....
I know this to be true as my two closet friends, men I've known for 53 years, own tool and die shops in MI and wouldn't hire a laid off GM die maker if they could avoid it.