According to Ken Walker, this fly is a mimic of a wasp in the family Braconidae. There is a similar wasp on this site, but not the same species as the the one Ken presents.
Classification
from Australian Faunal Directory
Order Diptera - Flies, 8955 named species in Australia at Nov. 2021
Suborder Brachycera - Flies having short or few-segmented Antennae ending in a style
Family Asilidae - Robber Flies, 383 named species in Australia
Genus Cabasa
Species Cabasa pulchella