I'm very likely going back to a flip phone, probably something like a CAT unless there is a tougher one that works on T-Mobile.
It's part of most multifactor authentication systems, as has already been mentioned. You could get by with SMS-based MFA, but you really should not as it is demonstrably insecure. In the future, these other methods will likely just go away as well, as they should.
At some point during COVID, a lot of restaurants stopped giving you printed menus, and expect you to use a QR code to access a menu on the web. Some provide printed menus upon request, but I've been to places that just don't have them anymore.
Here's a personal one: On a road trip a while ago, I stopped at a gas station to buy a map, only to discover that they don't sell them. This blew my mind: growing up, this is just what you did when you were in a state far from home, and you could count on any gas station having a folded paper map of the state in it. I don't think you can count on being able to navigate that way anymore, so you'd either have to plan ahead and buy maps, or buy a dedicated GPS unit, or use a smart phone for navigation.
Later on that same road trip, I stopped in a small town and wanted to walk around for a bit. I discovered that all the parking spaces cost money (fine) but that there were no parking meters or kiosks to pay at. Just a sign with a QR code on it, presumably pointing to a website or app download where I had to pay. In theory I could have pulled my laptop out of my suitcase, connected it to wifi somehow (not via tethering, but maybe a nearby coffee shop or something), and used the webcam instead, but come on.
My insurance company offers a "service" where they track your driving via a smartphone app. This is an optional service, and naturally I told them to screw off. It is not hard to imagine, however, this becoming not-optional, or being penalized for not submitting to it in the future.
Oh, here's another one: my last employer bought me a smartphone on day one of my job there. Not avoidable. I did not stay at that job very long, but I don't think it's all that unusual for companies to just assume you're going to use a smartphone and be in touch with them.
For MFA: I have an OTP client on my PC, as well as the ability to receive SMS using JMP Chat. MFA does not add much security for me since I already use long, randomly generated passwords from my local password manager, so I only turn it on if a service requires it for some reason.
For restaurants: I will tell the waiter that I cannot scan a QR code. If they don't have paper menus because they seriously expect me to have a phone, then I seriously expect that they have a phome that can scan it for me.
Navigation: this is a hard one for me. I have never driven in an unfamiliar location without a GPS. I am trying to minimize driving in favor of public transit anyways, but my roommate has a GPS unit that they said I can have. Will have to experiment with it.
Parking: this just seems so unfathomably dumb, even with a phone I don't think I'd park there.
Insurance: I'd change companies if mine required something like that.
I asked because I wanted to know the answer.
That said, maybe there was a sheet without QR codes and the nurse made a call that we looked like we had smartphones and gave us the QR code one. Can't rule that out.