As well, look at the job sites, DICE, Indeed, ZipRecruiter, Monster, and LinkedIn. Nearly 99% of the recruiters are Indian, too often even based in India, filtering out Indians and H1B for those American jobs. Americans are being hurt coming and going on this.
For trades, I suspect your main competitor for American jobs are illegals. And worse, if I understand correctly, when the government catches and releases them, they give them work papers so that they can find work. Nice, Americans less and less need to apply.
Illegal immigration is an issue for trades, though most the pressure there lands in Carpentry and Plumbing.
Thing is I have no problem with a hard working immigrants, even illegal if they really are just trying to make a life, They need to at least make it legal! (meaning illegal immigrants just trying to have a life need to come clean and get in the system)