Its not.

You've got nearly a century of past practice and the Railway Labor Act standing between what you and what you desire, and answers (or at least insight) to that which you seek can be found in Ernie Gann's "Fate is the Hunter". If you haven't read it, I highly recommend it.

I also suggest looking into a career in business aviation, as the "portability" of one's experience and compensation from employer to employer seems like something that might interest you relative to a 'traditional' seniority-driven airline career.