At the peak of outbreak we were seeing 4 week aggregated cases per capita in excess of 11-12 cases/1,000 population in Western amd South Western Sydney. And those districts had populations some twenty times larger than Albury's.
Also the huge matter of population density. You have to be in close contact to transmit/contract covid, which requires high population densities or large congregations on regular basis. The factors for transmission to get out of control in country Australia is just not there with simple precautions. Melbourne suffers greatly from high density and centralised gatherings, meaning covid spreads like a grassfire at the end of summer. Sydney has high density but much more segregated population with several main population centers separated by topography, that don't interact like in Melbourne. A bit like Geelong has weathered the storm fairly well due to it being remote from Melbourne both physically and to a point socially.
Country Australia is also very different in how society interacts compared to say the USA, which have more social interactions that promote the spread.