The reason it's called "G" and not "F" is because it was a pre-emptive naming to reflect the desired end-state. Nothing to do with reality.
Many moons ago when Australia looked at adopting the ICAO airspace classifications, the ATS that was being provided "OCTA" and various other requirements were not as specified for ICAO Class F (e.g. traffic information vs. separation to IFR etc.)
Closest i.e. a better fit was Class G and that's what is declared, with some variations from ICAO Class G which make it F-ish as
le P says.
ICAO permits States to provide a higher level of service than normally applies with a classification.