People like to complain about union dues, but after forming a union, you almost always negotiate a pay raise that is significantly more than your union dues. So you still end up with more money in your pocket.
What unions really are, is Democracy.
Right now, the workplace is a dictatorship. Or maybe an oligarchy. The wealthiest shareholders elect a board who hires a CEO who's word is law. (You might also own shares, but not enough to affect the election. Even if if all the employees below C-level voted together.)
But a union is real democracy, where each person gets one vote.
And it can have some of the same problems that other democracies have. But it's still better than a dictatorship.
Now, the. union itself is democratic, but it still has to negotiate, it's not suddenly in charge. It just has a lot more leverage to negotiate than you do alone.