So there's a downside.
As a highly-skilled contracting worker, I care nothing about changing my client companies policies. Their values are a curiosity to me. I negotiate my rate, do the job, submit my invoice and move on. So maybe I'm not the person who can appreciate the advantages in a full-employee situation.
you seem to be inferring that skill level should influence compensation, and since unions are primarily in the business of bargaining on wages, the downside is that they introduce some ceiling or whatever
but, that's not how all unions operate. many are focused on working conditions/presence of work/benefits alongside. your average SWE doesn't care about these things because their job is physically and mentally easy, plus they are wooed with free food/working conditions/intellectual challenges etc. so average software guy is sated and doesn't have much incentive to rock the boat.
but, let's run with your example. suppose there is probably a large amount of variance in ML engineers. suppose some have a skill set 1x (average ML engineer) and a few have a skill set 5x average
the 5xers like yourself (maybe) probably feel great, they have tons of disposable income and don't feel any particular pressure because their work is intellectually fulfilling etc. so no need for collective bargaining. don't hold me back! you say as you cash check after check
but, in the case of ML engineers, one thing they are creating is self driving trucks which is a market worth hundreds of billions of dollars! management throwing them $500k, $1mil etc. a year is absolute pennies relatively despite being a large absolute salary
were you to pipe up about this as a contractor, you'd just get run out of town. but unions may be able to take the collective and say "we are an insanely talented group of specialists worth 10x what you're paying us, so pay us... or we quit"
there are unions like screen actors guild that mandate membership but function as a sort of "loose" union insofar as they have extremely talented people alongside entry level people (high skill variance) vis-a-vis more manual labor (e.g. nurses, coal miners) whose variance in "output" is way more narrow
And if these ML experts fail to create an automated trucking system then will they be the ones to pick up the tab? Of course they won't. This means that the money spent on them still matters, because you're not guaranteed success.
If you can't handle the risk, don't start the company. If your business depends on you convincing people to take less pay, might not be a great company.
If you're saying "talented but lazy people who don't use their talent to provide value shouldn't be paid more" yes, we all agree on that. Nobody is trying to argue that point.
This is a misconception spread by capital to make you think unions are going to hurt you.
The media company I work for recently unionized. I assure you the junior staff still makes less money than the senior staff. What the union bargaining got wasn't flat wages. What it got was a higher wage floor for new hires, better PTO, more flexible working hours, and a consistent yearly raise/compensation schedule, things like that. No senior employee's work is devalued.
The tradeoff isn't between senior and junior workers. It's between workers and owners.
But are you really the best (non-managerial) negotiator in the entire company? Statistically speaking, the odds of that are low. And with a union, you could have the very best negotiating on your behalf. Yes, you'd have to give them all the information—but you have to do that now with your managers, in an adversarial setting, and you could instead do it with the negotiator in a friendly meeting where they're actively working to help you get them the information to get you the best deal.
Or, maybe you really are the best negotiator in the area. Wouldn't you like to get some extra pay from the union to be that guy above, and use that negotiating skill on behalf of the rest of the senior workers? (Don't think they'd pay you extra for that? Well, you're the best negotiator around—make it happen!)
Or maybe you not only genuinely believe there's no one who could possibly be better than you at negotiating your compensation, but also genuinely don't care that other people have the opportunity to be paid what they're worth, too. In that case, all I can say is I Don’t Know How To Explain To You That You Should Care About Other People.
No thanks!
So if your field is skilled programmers, why do you think a union formed by you and people like you would insist upon rigid pay scales, rather than pay individually negotiated based on skillset, competency, and demand?
Heck, even if there is a national union for your field, if there's no local, you would be in a position to significantly influence what route the local went.
And even if there is a local, if you joined it, especially if you're such a good negotiator as you seem to think, why do you think you wouldn't have any pull in determining compensation ceilings?
Plenty of places have wage schedules:
* https://en.wikipedia.org/wiki/General_Schedule_(US_civil_ser...
Throw a "Senior" or "Level II" or III in the position, and it can move someone to a different level.
I've also seen places allow for an extra boost via a "market allowance" mechanism.
Not a lot about 'Level III' in that discussion.
The middle-ground could be guilds like SAG/ACTRA: base requirements for working conditions and benefits, but clauses for independent compensation (but perhaps with a floor).
Tom Cruise and the guy playing Taxi Driver #2 are both card carrying members, but it doesn't stop Cruise from making more given that he's less replaceable than John Smith.
Isn't SAG an existence proof that this isn't necessarily the case? (This shouldn't be read as an endorsement of all things union, or of SAG in particular, just that it doesn't seem to fit the claim.)
It's weird that people have this idea that all unions always look/work a certain way when they're so varied from field to field (never mind country to country).
Off the top of my head, you could very easily have a union that says "These are the specific job requirements and expectations for this job. Here are the tiers of skill in this job type. Here are the floors for compensation at each tier. Here are the guaranteed rights and working conditions that the owners must maintain (PTO, Health coverage, overtime, etc). Any grievances will first go through mediation with a Union Rep/Lawyer available." and call it a day. That covers about 90% of what most pro-union supporters actually want to happen.