It is interesting that in the USA there is no requirement even in 2020 for ADS-B to be fitted to IFR or VFR aircraft if flying below 10,000 feet in D, E or G air space – unless within 30 nautical miles of a Class B airport such as Los Angeles or New York.
While what you have said is true it is also worth noting that the USA ads-b mandate extends to cover VFR aircraft too. When you factor in that their class C airspace covers a lot more airports because their class C is effectively any tower that also has radar you are likely to need ads-b in the USA in as many places as you are in Australia.
The big difference is the time frame and the cost of approving the installation. The USA mandate of 2020 means that industry is gearing up to provide solutions. The cost of compliance is dropping as new technologies are developed. Australia being earlier locks us into the higher cost of equipment. Coupled with a more expensive process for minor modifications to aircraft we have an overall higher impost.
If ADS-B cost $500 would you be opposed?