NATCA dues are 1.6% 1.4% of your base+locality (i.e. not including your differentials for Sunday and nighttime work) (and the June raise is 1.6%, so the dues pay for themselves on that alone). Obviously there are people who are pissed off about NCEPT and people who are pissed off about the COVID response, but generally the union fights for your career and your working environment... read the current contract and compare to the FAA-imposed work rules of the White Book.
I've heard that you especially want to be in the union as a trainee because while they legally have to represent you and your interests should you have problems with management or wash out, it's possible they won't fight nearly so hard if you aren't in the union. I don't think that would be an issue at my small facility but at a Z with dozens of trainees I could certainly see them prioritizing union members. You could see as scummy, but I interpret not joining as scummy—you're enjoying the benefits the union fought for (better pay scales, per diem pay for academy new hires, removal of dress codes, protection from management, the contractual June raise, ATSAP vs "three strikes," etc, etc) without chipping in to support the structure that made those benefits possible.
Of course the most grating thing, on a conceptual level, is that we legally aren't allowed to strike. (Side note, the big airport nearest to DC is the "Washington National Airport," it has no other name.) So any concession the union gets from the agency is not because the agency is afraid we'll strike but because the union has convinced the agency that it's better for everyone long-term if we get whatever that thing is. That does make me annoyed, and it makes our position as a union more precarious than non-federal unions. But despite that the union has won things for us, and they continue to be one of the more effective federal unions.
