Look at Bernie’s bigger picture. If we have those people (And I came from a family of lumberjacks so I fully understand their value) then those people ‘build things”. The LAST thing Bernie wants is more places built and opportunities coming from them. That is contrary to the central planning of socialism that keeps people dependent and CONTROLLED. And in contained cities.
People who can work metal can build guns. People that can work wood can build unauthorized housing. People that can work with power/electricity can help others generate it. People that can operate heavy equipment can get with the metal guys to convert them into weapons.
People with degrees in gay ethnic studies can sit in their cube waiting for the next scheduled 2 min. hate.
But the political ruling class still needs their homes wired, swimming pools excavated and poured, sewage connections maintained, etc....