The difference is the genetic inheritance of the US culture v the Australian culture.
Folks,
Lead Balloon's comments are all too true, and I would add:
Civil aviation administration in US has always been civil, the predecessor to the FAA, the CAA, grew out of the Interstate Commerce Commission, and in general, the military has to fit around civil aviation.
The military influence in FAA, as a result of ex-military employees, is as good as zero.
By contrast, administration of civil aviation in Australia started as a branch office of the military, and there has always been a very strong military influence, with many ex-military employees maintaining that influence --- and not limited to Flight Operations. The number of "engineers" in Airworthiness with nil civil aviation experience, and "honorary" civil licences based on military experience is a serious problem.
As for airspace, the "We won WWII, it all belongs to us" view still prevails, the extent of military controlled airspace, and military PRD in Australia is ridiculous.
Finally, something that will surprise no one, in the best of Australian "Regulatory" traditions (all is prohibited except that expressly permitted) Australia had a comprehensive aviation law, but sod all aviation, years ahead of the US, that had lots of aviation, but sod all aviation law.
The accident rates in those days were roughly similar, now it can reasonably said that our bureaucratic jungle of aviation regulation is an impediment to safety, based on the poor Australian air safety record, compared to the USA ---- and we don't even have lots of lousy weather and seriously big hills.
Mind you, I am certain that bureaucrats are proud of the fact that Australia leads the wold in aviation law, based on volume, weight or page or word count, take your pick.
Effectiveness or cost of regulation has never been a criteria in Cantberra, so aviation regulation is not an exception.
Tootle pip!!
PS: I see Albo is already banging the drum for rigorous air safety standards and enforcement, if he gets back on Saturday. Remember, the last Labor government boasted of their effectiveness and inefficiency, based on "new laws per. annum". More law equals better government, what could possibly be wrong with that??