5. Natural resources and industrial raw materials: Australia has a lot more fuel for an industrial revolution than South Africa, including oilfields, coal, natural gas, steel, aluminium and other precious metals, along with plenty of gold, diamonds and other precious stones and metals to get mass immigration from Europe off to an early start. And of course, tons of radioactive material to create as many nukes as they want, once it reaches that stage
6. Tech tree advancement: with much of Australia's soil fertility and water issues, and presumably a far larger population, there'd be more incentive for them to lead the way in any fields which could increase harvests and alleviate those water scarcity issues- such as the green revolution, hydroponics, R&D on selective breeding/cultivation, and later on, genetic modification.
7. Biowarfare 'Final Solution': Fun fact- do you know that the deadliest deliberately weaponized biological agent ever designed and released, across the world, was engineered and released by the Australians IRL almost a century ago? After the debacle of losing the Emu War 5yrs earlier, the Australians turned to biological warfare against the next species they wanted to eradicate from existence, the invasive European rabbit, and in November 1937, the Australian Council for Scientific and Industrial Research used Wardang Island to conduct its first field trials of myxomatosis, which established the methodology for the successful release of the myxoma virus throughout the country. And after 13yrs of development to refine and cultivate the perfect viral pandemic, they created the SLS strain of myxoma virus, with an estimated case fatality rate of 99.8-100%, and released it into the wild- facing the unexpected initial problem that their engineered super-pathogen was too deadly. But when less lethal (i.e, a mere 95-99% CFR) strains evolved from the one which they'd designed and released, which permitted longer survival of infected rabbits and enhanced disease transmission, it completely took over, and was subsequently taken and used to great effect across the globe.
Fewer than 1 in 20 European rabbits across the globe survived that first outbreak of the Myxomatosis pandemic, and it's still ongoing to this day, with a case fatality rate which still averages above 90%, and the species still afflicted by it to the extent that it's gone from being one of the most successful and abundant species in the world (believed to have outnumbered humanity itself prior to the bio-agent's release), to now being officially classified as an Endangered Species. So, then, just imagine taking that same methodology, of identifying and cultivating the deadliest possible pox virus for the target species, and applying it towards "killing off pest infestations" of Homo Sapiens Sapiens instead of Oryctolagus cuniculus. It's not unrealistic for an *Australian Drakia, because the real life Australia did it- they just did so against a species which they considered to be sub-human, which the world (and more importantly, they themselves) would benefit from being genocided out of existence, and wiped off the face of the earth. Which, for an *Australian Drakia, would be equally applicable to any and all non White Europeans as well...