Because government jobs are secure, Boeing subcontractor jobs where you are a cheap disposal cog are not. If you don’t see the value in security to someone making $20-$40/hr who needs healthcare benefits, you might start there.
A union fixes this in the long term, but that will take time. Government can employ rapidly. Something, quickly, needs to change before we forget how to build because MBAs, accountants, and lawyers burned the place down for shareholder value. There are two astronauts stuck in space very publicly demonstrating this.