Isn't the reason unions are hated by some simply that the know how to ask for more money?

No. The reason why unions are hated, (and by a lot of ordinary workers) is because they run rough-shod over everyone, including their own members sometimes, in their lust for power. I've known many instances where their demands have forced small companies to close down, loosing jobs for the workers. Even when the workers themselves ask for restraint, the unions will still steamroll over everyone. That is why the average union membership in some industries is only about 35%. In other Industries it is higher only because the companies are too scared to hire non-union labour.