LGS - that's a very over-simplified statement. Have a look at what a SWA pilot makes on the 737 and compare. It's mostly the pension costs and healthcare that's out of whack, and it's commonly referred to over here as the LCC's "juniority" advantage.
Younger workforce + not bothering with your retirees = cost advantage.
Let the public pick up the tab.
Having said that, there are still those (particularly the very senior) at the legacy carriers who try to do, and expect to do, less than a full day's work for their pay. 'I've earned it' just won't hack it any more.
