The difference is the genetic inheritance of the US culture v the Australian culture.
In the USA, aviation in all its forms is part of the genes of the culture. Being able to design, build, fly, crash, experiment with, improve on, fight in, travel in, and admire aircraft, is the USA. It's intrinsic to their sense of individual freedom and economic activity; and intrinsic to their sense of security through aeronautical capability and technological superiority.
In Australia, aviation has no intrinsic value, other than as a means of mass transport and defence, using aircraft designed and built by someone else, purchased on money borrowed from someone else. There is no perceived value in having an intrinsic capability to design and build aircraft, or in using them as a means of private transport instead of a car. Airports exist as pieces of monopoly infrastructure merely to make a few political mates rich. CASA exists to protect Australians from aviation.
Sad really.