I note from Flight Radar 24 that there is rarely an aircraft above FL410 over the Aus mainland.
You've been told a few times that FR24 only displays around 10% of traffic outside the "J" curve and capital cities/major towns.
From their site:
Why don't you have coverage in my area?
Flightradar24 only have coverage in areas where someone has installed an ADS-B receiver and feeds his/her data into Flightradar24. If there are no connected ABS-B receivers in an area, then there is no coverage in that area.