HR is not your friend, and several comments here say union, but unions go off the rails too. What avoids both kinds of problems? Simply different rules for how

HR is not your friend, and several comments here say union, but unions go off the rails too. What avoids both kinds of problems? Simply different rules for how the union power structure is populated? Entire organization is a co-op instead of owner + employees? Or is it already the case that union problems are not inevitable and when they have gone bad it was pretty clear how & why, and so no problem?