Australia has been using tap to pay for around 15 years now, whereas QR codes weren't in widespread use in the country until COVID. There's no reason to switch from NFC to QR given practically every bank's app natively supports NFC payments now (no need to use a third-party wallet if you don't want to)
The US is a different story... It took a looooong time for NFC payments to be adopted. I'm an Aussie living in the USA, and some of the US banks I use didn't support contactless payments until a few years ago!