Well, yes, but if there's a one-to-one correspondence between good unions and bad unions,that pretty much implies that the expected value of a union vote is zero. It's just the same as not unionizing.
In my personal anecdotal experience, the unions at the places I've worked have been mired in factions. They supported some workers but not others because they picked sides. They weren't just neutral, they undermined some workers to benefit others. It really soured me on them.
