Ah... Airlines and unions. Perennial anti-labor topic for many decades, despite the fact that the industry went from having very strong unions (and regulation) to having relatively weak unions or non-union (and basically only having safety related regulations).
I grew up (in the 80s) with my dad working for an airline, an airline which went from being unionized to being mostly non-unionized. I heard bitching about both union rule stupidity and management running roughshod over the workers stupidity. The airline was close to bankruptcy a few times, but only actually went bankrupt long *after* it had gotten rid of almost all its unions. The bankruptcy was due to many factors, of course, but obvious stupidity by management was way up there on the list of problems... employee pay and work rules were a minor factor, though they were hammered in reorganization as always.
Most of the big-name airlines are unionized (Jet Blue is non-union, and Delta is non-union with the exception of pilots), but many of the regional carriers are non-union. Furthermore, the big-name airlines have sub-contracted more and more of their operations to regional carriers, and, in fact, basically use regional carriers as a de-facto 'entry level' for pilots, maintenance crews, ect. From everything I've heard, being a young pilot pretty much sucks working-conditions and pay wise these days.
-- This is the root of the difference between those senior pilots with great pay and job security and junior pilots being shafted, not union seniority rules (except to the extent that the older pilots often have effective union protection and the younger pilots generally don't.)
BTW: The shift towards out-sourcing / sub-contracting to regional carriers is a huge deal, and has happened really quickly. It is the most important factor by far for in almost anything going on with the airline industry (or with workers in the industry), but the major airlines want to keep quiet about it since branding is so damn important... people seem happy enough ignoring the 'operated by' stuff printed in small text on their itinerary, but aren't generally happy if they actually think about flying a no-name airline.
PS: Again, Frontline did a couple of very good (IMO) episodes on the airline industry a few years ago... They are still well worth watching:
Flying Cheap
Flying Cheaper/