It's quite simple lads and lasses - supply and demand - RB pays his driver (of the always late trains) an above industry rate, because there are not enough of them to go around; a family friend told me that one firm trained a dozen or so, and most bunked off to other operators - no bonding you see - sound familiar; low time pilots hours build with a regional before moving to a bigger line.
Job satisfaction - would you want to be on the Circle line, not knowing whether it is night or day?