Unions have a purpose. Suppressing innovation and competition to protect their gravy train monopoly should not be one of them.
Unions serve a purpose in many industries but today a lot of them are antiquated echoes from the past.
Uber drivers should have a union IMO, but the ATeachers Union and Manhattan construction industry should have theirs disrupted by something more fitting for the new reality they have too much power. The construction industry literally have people holdning signal flags the entire day.
Furthermore when it comes to Manhattan lets not forget how much wiseguys control many of the cities industries.
Other places around the world can figure out to slow traffic down without having flaggers.