If you manage to implement national policy that sends 80% of the U.S. population into those trades, they'll pay a lot less. Simple supply and demand.
Like the CNC machining meme. If you reengineer society so that everyone below the top 5% of their high school class becomes a CNC machinist... it's not going to be a rare and valuable skill anymore.
Like the CNC machining meme. If you reengineer society so that everyone below the top 5% of their high school class becomes a CNC machinist... it's not going to be a rare and valuable skill anymore.