In your utopia, when all the “foolish men” who have been led astray by the evil teachers unions are retrained as web designers, what will you do when your roof needs to be replaced?
Pay a more reasonable rate for the dangerous job. I don't only think about my own personal needs, I'm also thinking about the welfare of those low paid men and their families. Roofers deserve more pay than hipster designers.
In that case, why on earth would you want to retrain them as web designers?
So the remaining roofers get higher pay, and the in-flood of designers leads to lower pay for designers.