If I asked them how we should be compensated as a group it would quickly be apparent they vote for the lowest common denominator.
You don't think that their answer to "how much should we be paid" would be more directionally aligned with yours than with your employer's answer?
The right question is - would my colleagues do a better job negotiating my compensation than I would?
Don't get me wrong - I think everyone does better with union negotiations (even managers to some extent - at least with a union contract, everyone's expectations are clear). But it definitely pays to be represented there at the negotiating table. It's a challenge to convince the younger workers to take an interest in this.
Probably. We often tell ourselves that we are better able to negotiate on our own behalf than anyone else, but the truth is that unionized workers usually receive better compensation than non-unionized workers.
To put this another way, if you said you were thinking about quitting, would your employer respond by offering a raise? If you were embroiled in some kind of scandal and had to either quit or be fired, would you receive a severance? If not, then you are not important enough to have any real leverage to negotiate your compensation. As an individual you are probably easy to replace, and certainly much easier to replace than the entire workforce -- which is why unions usually negotiate better compensation than individuals.