[pessimizer]

It's more a function of a state or municipality's negotiation with a particular union, and can be a rational decision for a municipality to make. The choice is between hiring only union people, or not being able to hire any union people.

[bobthepanda]

You could say that for ISP laws as well. "It's more a function of a state or municipality's negotiation with a ISP, and can be a rational decision for a municipality to make. The choice is between having an ISP/good broadband or not having one at all."

The point is that the mere existence of a union is not a sufficient condition for union-only laws; unions exist in places where such laws don't exist. As an argument against unions this is a slippery slope fallacy.