I think you have an unrealistic understanding of the labor/unemployment situation. I’m guessing you’ve never had to staff a blue collar enterprise for a couple decades.
A couple of decades, no. For several years a motor pool, civilian workers. Prior to that, for several years a credit bureau. I do know even then in a good economy, there were more people looking for jobs than openings.
Particularly now, with half of blacks and teens unemployed, adults working at McDonalds and Walmart because there is nothing else available, we do not need more immigrants.