Australia bans carriers from flying domestic flights to protect their local carriers, but international carriers are allowed to make one connecting flight by treaty all over the world.
Presumably the flights are profitable or they wouldn't run them, but it's Australia's fault that you can't buy a ticket not the airline's fault.
Why not pack the plane and get the sales? I am sure there's a reason (it's too obvious to not have occurred to an airline to sell tickets on a flight) why they think it's not worth it, I am just curious what it is.
Maybe it’s an attempt to avoid drawing too much attention from the regulator? If they started offering internal flights in Australia they’d be stepping even more on Qantas toes.
This is true for Australia, for India, for the USA, for the EU - an airline like Delta can fly to Sydney from LA but not sell domestic flights from Sydney to Melbourne. (Or, for that matter, international flights between Sydney and Singapore)
However, there is a catch! Airliners did not used to have quite the range they do today, and so the treaties allow things like refueling stops. And they (sometimes!) allow passengers to embark/disembark at those stops - but those passengers still have to be flying the international leg, or else it would be a domestic flight.
There's a Wendover video from years ago that's relevant: https://www.youtube.com/watch?v=thqbjA2DC-E
>I mean, they weren’t even selling tickets [to Adelaide] for the first few weeks. They were taking the p** out of the industry and the laws.”
which implies after the "first few weeks" they were selling tickets
The government is getting the industry protection from international competition that it wanted by banning the airlines from selling flights from Melbourne to Adelaide to fill the seats.
The airline wants to minimize empty seats and the government wants to allow domestic airlines to extract excess profit by protecting domestic airlines from competition but DGAF about empty seats. Therefore it is the governments fault that there are empty seats.