Pilot salaries are all based on union contracts. Union contracts are all negotiated by union leaders. Union leaders are all senior pilots. Senior pilots have a strong incentive to negotiate contracts that pay senior pilots the most, even if it is at the expense of new pilots.

I know a guy who flies less than 20 hours a month but makes well over $100k/year. He's been a pilot for over 20 years and knows how to work the rules so he makes money even when he's not flying (being on standby and such).