> And with anti-collusion labor protections, engineers stood to make even more.

Correct, but these protections exist (and existed at the time) independent from a union.

> In the US, union workers make between 10% to 30% more than their non-union peers

There's very few high-skill jobs which are commonly unionized. In a market where supply is greater than demand, then yes unions have absolutely shown to improve worker outcomes[1]. I'm not aware of any evidence for markets where demand outstrips supply (like that for skilled software engineers). It's not immediately clear that union protections would be beneficial.

>You're comparing pay across two different economies and only looking at unionization as a variable.

No, I'm simply pointing out that your flippant response to esoterica doesn't actually address the question. If unions are better for workers, why is it that a non-union area !!with a cartel depressing wages!! was still substantially better for workers than a unioned area with no such issue?

Saying "oh the market is different" ignores the question of why the market is different.

[1]: Indeed, that's kind of exactly what happened with this cartel. Facebook wanted to hire skilled engineers, and was willing to pay more, so broke the cartel. That kind of thing won't happen when workers are generally equivalent, but SWEs aren't.

> There's very few high-skill jobs which are commonly unionized.

Sure there are. Doctors and actors, to name just a couple. In both cases the "union" actively works to create barriers to entry.

The AMA colludes with medical schools to set artificially-low student body quotas. If you've ever wondered why teaching "XYZ for pre-meds" is such a miserable experience, this is why. You have to earn straight A's to get into med school because there are so many more qualified candidates than openings (but it's not clear to me how, say, art history or algebra-based physics makes you a better doctor).

SAG (the screen actors guild) requires actors to have already performed in a SAG production a a condition of membership. And they also strictly limit the number of non-SAG performers on SAG productions. That chicken-and-egg problem was very intentional

If you've ever taken a macro economics course, you know what effect these actions have on prices.

> I'm not aware of any evidence for markets where demand outstrips supply (like that for skilled software engineers). It's not immediately clear that union protections would be beneficial.

See above. Unions can create a market where demand outstrips supply.

> If unions are better for workers, why is it that a non-union area !!with a cartel depressing wages!! was still substantially better for workers than a unioned area with no such issue? Saying "oh the market is different" ignores the question of why the market is different.

So tell me why professional associations exist, then. Why do doctors form a union to increase wages, if as you say, they would be better off without it?

> Sure there are. Doctors and actors, to name just a couple. In both cases the "union" actively works to create barriers to entry.

Neither the SAG nor the AMA are unions in the traditional sense. In many ways, the AMA actively works against worker quality of life (consider that the horrible conditions for med students/residents and the high suicide rate among MDs) to artificially reduce supply.

>Why do doctors form a union to increase wages, if as you say, they would be better off without it?

The AMA is mainly a lobbying organization, not a union. Since a significant percentage of doctors are in private practices or small practices, they don't have representation with the government. So sure, the AMA does collectively bargain with the US Government. But by that same token, since 53% of MDs are self employed, the AMA can't do "normal" union things like set wages, because there's no one to bargain with except the doctors themselves.

And interestingly, the AMA actually admitted that its intentional supply-reduction is hurting the medical industry as a whole. To answer your question, "because they thought it would be better". But in hindsight, they probably weren't.