I'd just say that there are more reasons to unionize than just local monopolies. You unionize whenever there's a major disparity between cooperate profits and worker benefits. You unionize when work conditions are bad and management doesn't care. You unionize when you feel you are being treated unfairly.
For example, construction companies are often places where there's both lots of work available and union outfits doing a lot of good.
I'd just say that there are more reasons to unionize than just local monopolies. You unionize whenever there's a major disparity between cooperate profits and worker benefits. You unionize when work conditions are bad and management doesn't care. You unionize when you feel you are being treated unfairly.
For example, construction companies are often places where there's both lots of work available and union outfits doing a lot of good.