The unions and management have conspired to create a master/apprentice relationship between the "majors" and the "regionals", and we have all bought into it. As long as this relationship continues, nothing will change. It creates a "stepping stone" job and a "real" job. Combine that with the seniority system that rewards getting hired sooner, and you have the current situation.
Good luck changing a system that is designed to be this way by both our union and mainline management...