They're unionized but lack the ability to strike.
And, yes, it does make the union largely useless. They can file lawsuits, and cite law, and involve themselves in employee arbitration, but that only matters when the opposition engages in good faith.
At this point so many not-the-onions have happened that I had to check if it was a joke. I'm glad to see this is LSP, but I wish I could trade that reality for some of the other craziness of late.