A lot of the secondary cities in each state could become big in their own right.
Texas has a lot more people than Australia, yet it's a much smaller area & still has plenty of room.
https://www.sciencedirect.com/science/article/pii/S1353829222001605
https://www.infrastructureaustralia.gov.au/sites/default/files/2019-06/future-cities-paper-web.pdf
https://scenariojournal.com/article/made-in-australia
Of course one expects Melbourne and Sydney to have all the big stuff. However, from a Canadian perspective, it's amazing to see that Australia has a 12 lane crossing in Brisbane & a 10 lane crossing in Perth. Such wide bridges just don't exist in Halifax, NS & Victoria, BC.
https://en.wikipedia.org/wiki/Sir_Leo_Hielscher_Bridges 12 lanes.
https://en.wikipedia.org/wiki/Narrows_Bridge_(Perth) 10 lanes.
https://en.wikipedia.org/wiki/Narrows_Bridge_(Perth)#Railway_bridge:_2005 Seattle & Montreal would end up having their own version of a wide bridge with a train component as well. Of course, stubborn & backwards Greater Vancouver would be one of the last urban areas to ever allow such similar bridges.
It doesn't look like anyone from Canada was ever able to convince Australians to give up on bridge duplication & opt to just cram everything into 4 lanes or an inept 3+lane+bridge for two-way traffic.
