When I wrote about Google's new notifications of how it has customised your search results recently, I speculated that this feature might not be a high priority for the google.com.au site, since that already customises results to suit Australian users to some extent. That turns out to be correct, as Google Australia corporate affairs head Rob Shilkin confirmed to me this week:
This is Google.com only for the time being. We're always looking to roll out our features internationally if it will help the user experience, but no specific timetable for .com.au.
Note that accessing the main Google page via the 'Go to Google.com' link may not get you to that feature either, since Google continues to use your location to customise advertising and other features even if the search results are from the US site.