Unions may be different in your part of the world. In America, it's one of the only ways for blue collar or other production-oriented workers to have any degree of leverage at the negotiation table. We are treated like cattle in the workplace, and though unions come with their fair share of problems (due to it being yet another leadership structure to work within), the idea of workers holding power as a group is essential, because it reflects reality. None of that VC money is getting a return without workers to do the work. Most places in America are not unionized, but the ones that do pay better than other work in the area, even after union dues.

I see it as very much a union-by-union thing, much like you would an employer.

Now, some programmers may be able to negotiate good terms for themselves, but the vast majority of that stage is simply how silver your tongue is. Why should you be paid better because you got a better charisma roll with the interviewer? I would want my coworkers to be paid the same as me for the same experience. A senior with 10 years in the field, naturally, would be paid much more.

It's strange you say developers can negotiate, when there've been quite a few layoffs as of late and we see plenty of stories of people having trouble staying in tech. Which is it? The only thing that can give you credible sway is learning rarer or more in-demand skills, and putting together projects that show you understand how to use them. And for how long will that last? A union is a lot harder to fight than an individual.

But yes, there are bad unions. If they're as bad as your alleged blue collar friends say, let's name them! Sometimes their politics or dues or seniority system sucks. Those systems deserve to be put on blast.

But strangely, no unions listed in your comment as bad.