I think the point is that the word union has a particular stigma not shared by associations not called unions.
There are a lot more unions in the US than people realize. For some reason (I can think of many), high-status workers in the US are captivated by the drama of a few particular unions, and have extrapolated wildly from it.
(Happy to concede there are unions people like, but if that's your best effort at naming two good ones, I think the problem is worse than you're acknowledging.)
If your argument is that people have negative opinions about unions, well, respectfully, no shit. My point is that those opinions are not well-founded.
"Some will rob you with a six-gun, And some with a fountain pen." -- Woody Guthrie "Pretty Boy Floyd"