What exactly does the term "natural wage scale" mean in the context of this?
Well, I’m not sure I want to start a debate about language here.
Namely, what is - or, what is not - external intervention.
My point is that overt government policies on immigration have flooded America with a huge oversupply of labor, most of it low skill, low education labor.
When the supply of labor is larger than the demand for labor, wages go down.
And that is exactly what has happened in America for the last 20 years.