hmm QR checkin...yes I do it without fail & do see many do it, but certainly the fall back is you get put into 14 days iso from tier 1.
I imagine bugger the QR unless asked, watch the DHHS website (as I do) and if a store/location comes up that I suspect I've been to, just be very watchful for symptoms & just go for a test regardless after few days (with a fake cough etc on arriving for test)
Fair amount of common sense would be req'd by an individual to play the above.
I say this as still so very unlikely to have caught covid just cos attended a tier 1 location.
above off topic, so I'll throw in my prediction of international travel, NSW & VIC November, ACT December, that's all I dare to predict.