I would really hate to deal with a second level of bureaucracy when it comes to promotions and such.... let alone employer's having to accept "this guy is a senior X now" and realize he is not as opposed someone else who wasn't given that chance. That still seems like a very track type of career path situation where the technology world is still fast changing and has huge amounts of variety.
I was imagining it more as peer-accreditation and peer-participation, as the other union members would be your peers. Basically more democracy rather than bureaucracy.
"Based significantly on" is not the same as "made by" or "made in collaboration with." The problem here is an employer using their discretion as a hidden means of retaliation, and they can still do that with all the feedback in the world as long as the discretion is still all theirs.
> If there is any room for an employer to make a judgment call then they can make it, and a union has limited ability to deal with that...
US-style unions are really only just once instance of "unions." I can imagine another instance, where the union itself is both independent of the employer but also has a significant power in promotion decisions, that could deal with these situations better. That's getting toward a decision-making structure that formally represents multiple stakeholder grounds instead of just capital and its representatives.