Earlier quoted context omitted.
Collective labor action is a negotiation, so I guess your point is that employees can "extort" you with the "threat" of a fair negotiation? Using that kind of sensational language to describe something routine makes it hard to take you seriously.
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.
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?