In my area the Police make middle class wages. Thanks to generous taxpayers. If you work in a tax payer sheet metal fabrication factory you make maybe $50k in my area. No unions.
If you are a sheet metal duct guy HVAC, for REAL ESTATE, its unionized and they make a lot of money. Like a cop I guess.
I always suspected that because of military contracts, and the greater good for fabricating companies, it was important to keep metals prices and factory labor cheaper.