There seem to be a number of elements at play that are preventing a more coordinated approach
Border closures to date have been inconsistent across states and territories. An event in one state will result in different national travel rules for residents depending on where they need to travel to, and different states also respond to equivalent events quite differently.
For example, Victoria has put the entire state into lockdown with the most recent Holiday Inn hotel quarantine breach, whereas Western Australia and Queensland focused on the more immediate urban areas where potential exposures occurred.
Read the original article at The Guardian