Dick
In Australian Class G, are you required to have your VHF switched on if you're VFR and nowhere near the vicinity of an aerodrome at which carriage of VHF is mandatory?
Maybe the problem is the belief that if a radio is fitted it has to be switched on all the time and monitored all the time. You might find that the Australian rules accommodate the UK approach, but the obsession with radio calls means it doesn't happen as a matter of practicality.
And note: I'm talking Class G away from the vicinity of aerodrome at which carriage of VHF is mandatory.