Mark Patinkin tells an interesting anecdote in relation to the Central Falls teachers’ firing:

I have been in a union for 30 years, and have come to feel that in standoffs with management, members often get into a collective self-righteousness that makes them vote against their individual good. …
In the mid-’90s, I was reading a union publication that proudly featured a service being offered to striking journalists in Detroit. The service was a mobile food pantry in the back of a truck. It was visiting a picket line. There was a picture of newspaper people “shopping” for handout food in the pantry. They needed the service because they’d been out of work for a long time.
My reaction: Why is the union proud of this?

I’m not sure how Mark’s union is or was structured, but in unions with national organizations behind them, once you get beyond the particular employer, striking doesn’t affect the union leadership. Indeed, the disruption and realization of the threat contribute to their power.