But passing down through 8500 feet on the way to Ballina on the NSW north coast, air traffic control leaves the plane to its fate. The rules dictate air traffic control can no longer direct it below that altitude.
It's a little disingenuous to imply that the aircraft is 'left to it's fate' by ATC. IFR aircraft will receive traffic info including VFR aircraft observed on radar. That is the key,
'on radar'
Give the ATC the tools and they will use them. Continue down the road of no surveillance and there's nothing they can do. Unless you want a procedural approach service. 1 in, 1 out.
If you provide radar or ADSB coverage to the ground, appropriately sized sectors and the staffing required, ATC will be more than happy to 'approach service' you to the ground.
Read the above paragraph and understand you will
NEVER get the above service in Australia.
NEVER. Aviation is Australia is not seen as infrastructure or indirect investment in the economy. It's seen as either a rich boys play thing or a pain in the arse.