Not all, but many restaurants in multiple cities. They use QR codes, no doubt to identify you better (tie you to a specific place and time, maybe to a specific table). Usually I just load the restaurant's website on my phone and read the menu that way.
I was also at a play where a QR code was the only way to get the program.
What exactly are you suggesting the QR code is doing? My phone shows me the URL encoded by the QR code before opening, and I've never seen one with any additional information in the URL. They're not dynamically generating QR codes for you...
The static URL encoded by the QR code funnels you to a web page where that page view can be reported back to trackers and incorporated into your advertising profile.
Using your device to read the menu puts your device in the loop where formerly it was not.
Sure, if I suspend disbelief and assume that no other search engines or navigation services were used that do similar tracking—but the GP was specifically calling out QR codes, and they use the website anyway.
You don't have to suspend disbelief to come up with such a scenario. When I go to the bar down the street from my apartment, order food and a drink, pay cash and then leave, it was not an interaction that was likely to become part of my advertising profile. Now it is.
It's not comparing websites accessed via QR against every other already tracked thing in society, it's comparing it with laminated pieces of paper.
Have you used them at restaurants? I've avoided it, so I don't know.
I didn't mean they generate QR codes dynamically. It wouldn't be hard at all to encode the table number, for example, and then of course they have the time and know your reservation, and thus can identify their customer's phone.
Not quite the same thing, but I had to head home early one night recently because my phone had died (which almost never happens to me) so I couldn't show vaccination-proof. I would guess that a person's phone dying while bar-hopping is much more common than dying while dining alone (since when dining with others, you can just look at their menus).
You're not wrong that this fundamentally excludes those who don't have (powered-up) smartphones. But it's not like restaurants and bars had the luxury of thinking through and choosing to have these effective new smartphone requirements: they adapted to Covid for their survival, and the odd case who got unlucky with a dead phone is just collateral damage.
Well yes, the point of this subthread is not that it's impossible to do this well, but that bars/restaurants don't seem to care whether they're excluding the occasional unlucky customer. I'm in New York City and not a single person has scanned my vax QR code: they just see a vaguely official looking app with a name that matches my ID, or a physical vaccination card (conveniently sized to not fit in any wallets).
Also, in your case, is this a federal system or a state by state one? If the latter, this sounds way worse than what NY is doing; with my CA vaccination I couldn't get in anywhere.
Is this really true where you are? No menus?