Somehow I always get downvoted for saying that, but I worked at a place where all developers (well, everybody) were unionized. Magic did not happen. Bullshit did.
But I don't think most people go to an interview without having googled "how to ..." about the interview process first. Thus even those not naturally talented at negotiation have a reasonable chance at negotiating decently.
Talent/job competence + a little bit of research and preparation prior to interviewing will ensure superior results IMHO.
Unionize and wage equity magically disappears.