To do it properly, you’d need different zones (higher charge in congested areas for example), but that would require creepy GPS tracking, or creepy ANPR everywhere. Really not a road we want to be going down as a society I think.
They could just double the cost of rego for everyone if they’re so concerned about not getting a tax they don’t get already (Fed Govt does).
The only major difference is that sometimes you can not avoid going pass a road toll. However the same can also be said about finding a parking space, and parking data is likely much more detailed information than passing the edge of a traffic zone. Many parking spaces in the city where I live have also moved over to use ANPR, which kind of mean the two concepts has already merged to a degree.
The per km thing is a bit creepy even if it's just reading the odometer, and as you say a bad deal for regional residents.
It's also very viable to not own a car in the city. I don't have one. But in the country, what behavior are you trying to encourage? So that complicates things.
It should probably be means tested too.
I just object to the idea that EVs should be subsidized rather than ICEs punished. It puts the finger on the scale away from even better solutions like riding, walking or public transport.
Oh, wait, that's exactly what Victoria has done: https://www.solar.vic.gov.au/zero-emissions-vehicle-subsidy
Personally, I'd keep the EV tax as is, remove the subsidy, and significantly increase the ICE tax. Cars are awful, and their negative externalities don't stop at CO2 emissions.