If safety is the prime concern on this thread then why doesn't every owner of an aircraft with an engine spend a few thousand dollars an fit a transponder? I have one on my 1970s Pa28 . So ATC can see me and RPT can see me. If E is lowered to the frigging surface I won't need to worry if it is AGL because I can pop in and of E without a care in the world.
In 2021 it is the dumbest argument that owners cannot afford to fit life saving equipment on board their aircraft.
if you want to fly in the vicinity of a fast RPT aircraft like at Ballina or Wagga or Hervey Bay, use your radio, light up your aircraft, purchase and fit a transponder or ADSB and use the device to mitigate your 1960s 172 smashing into a 737 with 150 people on board.
I have flown extensively in USA and UK. The airmanship in Australia in GA is left wanting in comparison. The argument that Class E can't be lowered to separate IFR (particularly RPT) because owners of bugs smashers don't want to fit life saving transponders or ADSB , is beyond comprehension.
Coroner: "why wasn't there controlled airspace when the capability existed?" " oh we did not want to upset pilots of light aircraft by asking them to spend a few grand on a life saving device" too expensive. I would not fly without a transponder with my husband and kids on board any more than I would not fly outside VHF range without my HF radio.
time to mandate common sense.