Considering that the F/O is the apprentice Captain, it is only right that a fully-qualified LAME be paid more. He is worth more to management for the simple reason he is much harder to replace than the F/O.
If QF LAME's are paid only half the rate going elsewhere, why don't they piss off elsewhere? Because they crave job security or the staff travel or stable rosters or the particular QF main bases perhaps? There is usually an underlying reason why people put up with seemingly lesser conditions than what are seemingly available elsewhere. And does that quoted rate of $52 K include overtime and shift allowances? Maybe the other mobs are on a flat rate and have to work every weekend and back of the clock. I dunno, I am not a LAME, but find it hard to believe the small players actually pay MORE than QF for essentially the same skill.