If its to protect the worker, well - they wouldn't need protection if they simply did their job for 8 hrs a day.
If its about seniority, well - here in the real world, there is a big difference between a 20 yr worker who is so used to the union lifestyle that he has lost his work ethic and whines all day long - compared to a 10 yr worker who is eager.
If its about coasting to retirement with as much free benefits as you can get, well - why do you call yourselves "the real American Worker". The real American Worker actually works and takes pride in his work and doesn't need a union to create a delusion of pride and intimidation into the workplace.
If its about creating a paycheck, bonuses and health benefits for Union Leadership on the backs of the union employee, well - mission accomplished.
Seems to me, its about weeding out the workforce every few years. This is needed to make room for the new hires. Oh well - that's the unions call.