A 30% wage delta is huge. On a like for like basis, in some categories, it may be the case. If so, it is illustrative of excess costs that do exist in some QF job categories.
I am told that the JQ engineers and ramp staff are on broadly similar pay as the QF people, albeit with efficiencies written into their agreements. Certainly cabin crew pay scales are different. And pilots too, to be sure. As time goes on though, all revolutions morph into what they once revolutionised. Costs generally approach the mean: long service leave, sick time, retraining all erode a once significant advantage.
That said though, I will again observe that even if everyone in a LCC carrier worked for free, it would equate to a total cost savings of around 30%. But what fraction of a legacy fare can you charge to entice the punter onboard a second time? Revenue is the silent, unfashionable part of the profit equation that you never hear emphasised. Yet no one has ever heard of a Low Revenue Carrier. Or at least not for very long...