You say that your voice is only as good as the people representing you - why don't you represent yourself - you can legally and are allowed to do so, without the union if you want ! Old fashioned but true - if you think you can do better, do it is my point !
The union doesn't vote on your behalf(or for others) tho ferrari - still needs 50% plus one when it comes to vote time. The crap deals you talk of, were still 'agreed' to by a majority. If your not willing to sit in the negotiating room to get a better deal, the least you can do as a collective is vote no, and be willing to do something (industrial action) to improve the offer on the table ! That might mean losing some $$ in the short term, which a lot are never willing to do.
The deal you get - is the deal you are willing to accept or be willing to fight for better. The union isn't just the ones at the table, its a collective of all the pilots, members and NON members, as you point out, the union and the negotiators put the best offer they can get on the table, and there is a VOTE !
Complaining you got a crap deal because the union is crap is like blaming the gym because you don't look like the rock, but you aren't willing to go to the gym. Everyone needs to go to the gym(not just join it), and put in the work to see the results. You all won't look ripped on the basis of the work of 5 people turning up everyday willing to work out for 5 hours, while you sit at home on the couch.
Sadly everyone wants the awesome deal - but for everyone else to do the hard work thats required to get it, and quietly blame the minority that work their asses off(in their own time mostly!) to fight the evil empires alone. Remember you as a collective - ARE the union.