Back in the 1970s and 1980s it was expected that you needed to go to a country's main city for a long haul flight, it wasn't much of a problem as you could only afford to do it a few times in your life. British Airways routing was LHR - BAH - SIN - PER - SYD. Brisbane didn't even have any night life, let alone a need for one stop to Europe. The Middle East airlines were able to make secondary cities viable because they could connect passengers through a hub. Emirates can offer Adelaide to Glasgow with one stop, QF can't.
In the UK, the equivalent of the entire population of Australia live within a reasonable travelling time by road and rail from Heathrow.