That middle-man has more power than you do in a huge number of cases. There are very few individual workers where the bosses will suffer mightily if they refuse

That middle-man has more power than you do in a huge number of cases. There are very few individual workers where the bosses will suffer mightily if they refuse to work. But almost every boss will suffer mightily if a huge portion of their workers refuse to work. That is the leverage unions have over the bosses that individual workers almost never have.