Because they simply don't test!
(for comparison: Germany: 2200000 tests per week!
#CoronaAbsurditäten #CoronaStupidities #Corona_Blase #Corona_Bubble https://twitter.com/GidMK/status/1354517209373052929 …pic.twitter.com/iKW5uRGVeM
You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more
Lol! 
The TOTAL number of tests conducted in Australia is just 12,8mio.
Germany does this amount in about 6 weeks!pic.twitter.com/xOuGSUhFHs
I mean, you're making a truly very silly argument. As you can clearly see, we do a similar number or MORE tests per capita, although it dropped when we had no cases for 2 months. Why does Germany do fewer tests than the USA?
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.