Not wrong here LOL if you noticed I said Thailand in my 1st post and how it works hereWrong. If the QR leads to a website or app to pay online using a card -which is what most payment QRs in the US actually do- then there is still the 3% card payment fee, and perhaps even more than 3% due to the higher risk of fraud of a card not present transaction vs card present.
All local banking apps have QR/Bar Code readers as these are used by utility companies, government bodies and Vendors
The Utility companies code are direct payment transfers from your bank app but include additional info ie your account number with them, so they know who sent the transfer, its instant and you can check payment received via their app too
Simple vendors QR codes (eg restaurants) are just their bank account details (saves you typing it in especially with Thai names LOL) where you send the transfer via your banking app and they just want to see transaction complete on your phone (some take a photo of this)
I haven't lived in the US for over 10 years at that time BOA only had cheque scanning, so can't comment on what's possible now
As I said this is all simple safe and secure and keeps costs down and businesses open