"Collective labor action" is another kind of threat used against managers who might otherwise accept a better offer from other workers. We've surrendered and begin to encourage unions to perform their extortion in open court to reduce the body count.
The threat is not "a better deal or we'll quit", that's a perfectly fair response to unacceptable conditions (and "other people will take this deal" is a perfectly fair counter). The threat is "it'd be a shame if something were to happen to your business, like a lawsuit or a fire". That's the difference between negotiation and extortion, and that's what's behind all the union/mafia links.
A collective labor action is literally "a better deal or we all quit." Why do you assume that unionized developers would resort to violence or baseless litigation?
Medical doctors, university professors, and librarians are largely unionized. Do you believe the American Association of University Professors threatens colleges with arson when negotiations aren't going the way they want them to?
> Why do you assume that unionized developers would resort to violence or baseless litigation?
History?
> Medical doctors, university professors, and librarians are largely unionized.
Doctors aren't exactly a union - they're a licensing body. That distinction matters rather a lot for this discussion. (No licensing body has ever threatened, let alone carried out, violence to prevent outsiders from taking jobs, to the best of my knowledge, but unions have done so regularly. On the other hand, licensing bodies have the authority of the state behind them, so maybe it's just somebody else who does the violence...)
You're thinking of state medical boards, but the AMA is a non-profit that engages in extensive lobbying and, via the American Board of Medical Specilities (http://www.abms.org/about-abms/ ), exerts some degree of control of their profession. (I.e., you must join an organization and demonstrate proficiency to call yourself a "board-certified pediatrician.") The AMA calls themselves "more than just a union," and many members are self-employed, but I think it still constitutes a union.
You're right that the AMA has never threatened or carried out violence, but then again, neither have any professional unions I've ever heard of.
For the record, I've spent ~6 years in unionized workplaces and never heard the school teachers, university professors, or government employees who had union cards conspire to commit violence. I would recommend reading about professional unions before decided that they are violent based on "History?".