Checking logs of a state-run server is way easier.
Which would be a local telco.
> QR codes aren't effective at all as a surveillance mechanism. Why the hell does the government need to monitor which venues you visit based on QR code check-ins? They literally just ask Apple, Google, or any other big tech company about your phones geolocation and IP log history to monitor your whereabouts.
This is about locating a user based on QR code scanned at a venue. All I’m saying: no need to ask Apple or Google. Your telco already knows you have been at a location at the time of the venue.
Telcos can calculate approximately where I was (with accuracy worse than raw unaided GPS - so ±10m at least, and unpredictably wrong if I'm behind a wall or in a vertically built-up area) at a particular point in time - but they don't know the exact timestamp to look for.
Most people with accounts to these platforms have credit-cards, payment history and communication with others. There is nothing particularly special about vaccination QR codes being more unique than any of the other multitudes of data you already provide, willingly, to these tech corps.