Here in Finland most everyone belongs to an union of some kind or benefits from having one in their industry even if they don't belong to one.
The unions negotiate our collective labor agreements because as a union they surprise surprise have a way better negotiating position than an individual could have. They offer legal services to their members, organice industrial action, give member benefits such as trips, classes on various things, cheap(er) cabins for their members to rent etc.
Almost anyone with half a brain can tell that that is just useful and overall better for the worker.
It's also just easier for companies to negotiate with one party rather than every one of their employees so they generally understand their benefits too.
So when you take all of this in account why the hell do so many americans still hate the consept of unions? Do they just actively WANT to make their own position worse?