The short of it is that population density is the prime driver of this thing and then how communities interact, which in the case of QLD and WA it's really not a big threat. Vic has a more European style of interaction and dense population that converges around the city center, then throw in the communities that have large extended families and large community gatherings for whatever and you have the perfect spreading ground. I would hazard a guess that Melbourne also has a very high amount of older population concentrated in retirement homes which adds to the death rate. I doubt WA would get a massive outbreak even if they did let it rip, but I don't really care what they do, its their turf, their rules. Something for the voters of WA to sort out when the time comes.