Since CX normally sell L and H class exUSA, they have managed to price the PEY fare classes in a more competitive manner. I'll admit if the AU$ falls far enough then perhaps things will be competitive. When the AUD had parity (or higher) the situation was even more ridiculous.

Example Round trip PER-LAX (or reverse) two Tuesdays in Apr
exPER E class AUD 3991 about USD 3180 today
exLAX E class USD 2681

The difficulty is that CX would have to lower the ordinary Y class fares exAustralia to permit equivalence with the exUSA fares. That won't happen.

Back in October the PEY (LAX-HKG-PER) cabins showed a reasonable selection of seats a week before the flights. Both ended up oversold. Perhaps a shuffle up from a Y cabin oversell. Sunday HKG-PER seems a good day for op-ups. Or expensive last minute tickets.

I would venture that the middle east and south Asia have a different clientele. If they can afford to fly in a better cabin than Y, they will pay for J.

Happy wandering

Fred