During the last mining boom it was the “marginal profits” of trans continental and intra WA that funded the ridiculous capacity war on the east coast, a senior executive told me of his frustration watching massive profits from WA being eaten away by empty flights every 15mins between Sydney and Melbourne.
Perth runs make some profit and mostly for QF in the business class area. Until the early 2000s Perth was a backwater with few flights that cost a fortune under the duopoly. Virgin tried at wide-bodies and struggled to make anything of it, it was fairly well known they were breaking even at best on the route with those and the 737 fleet was doing the hard yards. I flew with both QF and VA on the A330 and 767 products regularly, there was always an empty row of seats I could stretch out on for the last 10 years some flights being 1/3rd full. The 737/A320 flights were always full and uncomfortable. Ticket prices were nothing compared to the AN days being 1/4 of the actual prices they charged back then, not even adjusted for inflation.
Melbourne, Sydney, Brisbane merry go round is the money spinner, and if you are not cashing in on that, you wont be around long.