Aeromedical alone is worth 2%. The whole thing is "job insurance". Not expensive when you look at the liability aspect. Whether it's your job (scope), being able to work (aeromedical), or contractual provisions impacting daily life (QOL), EFA for negotiations, or a disiplinary piece, it's easy. Sure, nobody wants to see 1.9% of their pay gone, but it's a tax deduction and also a job insurance policy. Alpa isn't perfect, and no Union is, but no Union at all is seriously rolling the dice. It may work well in initial growth and a positive economic climate, but in any downturn it's a catastrophe. If faced with a carpet dance, even if completely right, it can ruin your career and livelihood. Representation is huge. The 5% of "problem children" will keep their jobs, even if they shouldn't, but 95% benefit. It's good "pillow factor" at the end of the day.
As someone who has had medical issues, and also served as a rep to keep folks employed, the positives far out weigh 1.9% of wages. Heck, for most the first contract is a pay bump that covers the cost plus some. Whether it's industry parity or leading the pack, it's better than hoping to get what others have. Why? there is at least some leverage when being able to function as a combined and legal group.