Well, you live and learn! I always thought that phones gained NFC after credit/debit cards (that is, to emulate cards) rather than vice versa as you seem to suggest.
Indeed, so virtually everyone with a credit card has access to it at this point. Penetration of the technology nears 100%. Why reinvent the wheel?
One thing I have noticed about NFC transactions if that the user rarely gets a paper receipt showing the amount charged for later comparison against the bank statement. They are too concerned about convenience. I'd expect these folks don't even review their credit/debit card statements. So, there is a greater chance for undetected fraud.
So ask for one? The process on the pin pad for receipt generation is usually identical whether contactless or contact payment is used, and depends mostly on the merchant's policy. This has nothing to do with NFC.
I advise people that are concerned about this issue to either request non-NFC cards or drill a hole to break the antenna. My (45 and 30) kids love the ease of use. I am much more concerned about security than they are. To each, their own...
If you don't like NFC that's...fine...you can disable it and use contact payment instead. But that doesn't make those asinine beliefs justification for a new system that serves the same basic purpose just...worse. I was under the assumption that we were being rational here, on a technical forum, and that the above discussion of the security model around NFC was enough to get past that. So thank you for reminding me that's not actually the case and that we need to spend more time emphasizing that NFC is pretty secure as long as you remain in physical control of the card/device. Just don't give your card to anyone and the NFC-related risk is effectively zero.
One reason I suggested QR codes is because my bank uses them effectively to perform 2FA using a phone. My local supermarket uses them for purchases (to perform the same function as NFC). My phone doesn't have NFC and my PC doesn't have an NFC reader, so QR code has made life a lot easier for me. If your phone has NFC and you use it then you may not fully appreciate what the lack of same means when you'd like to use that feature and can't.
There's no reason such a system couldn't work, but it has a lot more dependencies and limitations than the NFC system. You can't reasonably implement it in a credit card, or many other devices you might want to put it in like a smartwatch, since it requires a camera. It depends on an active Internet connection on the user's device. I'm not seeing much benefit here.
I don't actually bother with phone-based NFC, it's not really more convenient than just tapping the card, but it's handy if I forget my wallet.