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Qantas offsets some of the losses on LAX flights by doing maintenance while the plane sits. I don't recall if VA does the same, but that could contribute to QF's higher performance.
VA indeed did some basic maintenance at LAX - it was not uncommon to see a VA 777 inside one of the "Qantas" hangars to the West of the terminals.
The LAX routes had been making money, but as you indicate VA do not publish performance by route.
This link makes a statement re profitability:
https://simpleflying.com/virgin-aust...-fleet-future/