WRT us being 'one of the least efficient' airlines, this is an oversimplification of one aspect of running disparate fleet types. At one end of this spectrum you have an airline like SWA, running one aircraft type, keeping it in the air as much as possible, along with the crews. At the other end, you've got us, running 15 types through hubs, our pilots often sitting for hours waiting for a flight.
On the face of it, from a pure hours operating standpoint, we are less 'efficient'. But when you factor in hub revenue dynamics, right sized hulls at the right times, code share multipliers, and the increased revenue from HVC initiatives and upsales (business class and econo comfort) --- we produce more, much more... revenue than our contemporaries on a per-pilot basis.
That's one reason. Another is this: we run a safe, reliable operation, all over the world, 24\7\365. What our pay says about us is important----that we're worth it!