Look at the backlog of grievances at union regionals, how are those usually resolved? "Ok we won't do that again..." Look at how corrupt Eagles Union is, charging alcohol by the thousands of dollars. People aren't unionized at Skywest not because they care about 2% due payments (well some do I'm sure) or because they love SAPA, it's because they've seen the ineffectiveness of unions at the regional level, for example, eagle, com air, pinnacle...where were the unions when things went south? A union that represents both mainline and regional cannot in fairness equally support both pilot groups, since the goal of mainline pilots is their QOL and returning their flying or protecting their current flying, which of course has a direct impact on a regional Pilots QOL.
Unions are effective when there is transparency, leverage and unity, none of which are on offer at current unions. A Regionals livelihood is based on flexibility, because if you can't give a partner what they want, they will most certainly get it somewhere else. Think pilot shortage is a problem? Show someone a quick upgrade and they will trip do whatever it takes to get into that position, PSA and Compass aren't having trouble staffing because they got an abundance of new flying and this will continue, it's continouis cycle of flying being moved around from one regional to another.
My point is, get your time and get out if you can, no regional is ever safe.