I see. I'm a bit sad that for example the regional chapter of the FAU (Freie ArbeiterInnen Union) would not be as effective as my membership in verdi. I sympathize with FAU in spirit, but verdi (supposedly) is big enough to get anything done.
My personal experience with verdi is kinda not good I guess? Like I have to call them up again as being self-employed + being a student you get shoved into one small sub unit in the federal state I'm in, and my problem back then was forgotten.
Other people think they are good, so it depends on the job I guess.
A friend of mine was thinking about specialized union for programmers a while back.
My father's family side used to(?) be in unions for large parts I think, coal mining traditions until they've shut it down here.
FAU is like, rooted in anarcho-syndicalist structures iirc.
I'm not saying the big ones (more than 3) are not political, they suffered big hits during world war 2 (basically almost all union bosses send to KZs, money of unions merged into the biggest nazi workers union) and they had to rebuild after it was all over.
It seems like the percentage of union members is fading since the 1990s, but I'm not sure.