I agree. I bought my SkyEcho2 in mid 2020, as soon as they were on sale. Before that I had a small 'Ping' ADSB-IN gadget. So I'm definitely more of a believer than a dreamer in the EC device department. ;- )
But, when it comes to public policy, the reason the government might (in fact, does) choose to subsidise GA ADSB uptake is that 'our sport', whilst a user-pays activity, has the rare capability of bringing down an airliner. And then there'd be hell to pay. In fact, it came to within a bee's dick of just that in Nov. 2020 near Ballina.
https://www.atsb.gov.au/publications/investigation_reports/2020/aair/ao-2020-062
Anyway, the feds have at their disposal, both carrot and stick levers and, right now, they're giving the former a bit of a pull. My suggestion earlier in this thread was just that their plan might have worked better if the carrot had been a wee bit bigger, and a bit sooner, but, in any case, I'm not holding my breath for that, and I'm not hanging out for a subsidy.
This piece in Australian Flying a year ago puts it in a nutshell:
"The results of CASA's VFR equipment survey has provided the regulator with a view of GA that they never previously had ... But one thing that has raised some eyebrows is the lack of ADS-B use in VFR aircraft. CASA mandated the system for IFR, but has consistently maintained an encouragement policy only for visual flight, culminating in the development of a non-TSO standard for VFR, known as conspicuity devices. But the data shows that around 57% of GA aircraft and a whopping 83% of sport aircraft have declined the invitation to fit any type of ADS-B. ... what it means is that there are a lot of aircraft getting around that the ADS-B system is blind to, which dilutes the efficiency of the technology. It is hard to believe that, after seeing these figures, the word "mandate" has not been uttered between the walls of Aviation House.
https://www.australianflying.com.au/the-last-minute-hitch/the-last-minute-hitch-1-october-2021