> So I assume that even though QR codes are available where you live, you use your debit card with an NFC chip because it is quicker than using QR codes...

Yes, I generally use my card rather than than QR unless the shop doesn't take cards, doesn't have a paywave/etc-enabled card reader, the card reader is broken, the sales person doesn't know how to use it, or the sales person insists I give them my card and PIN to pay (none of those are hypotheticals, I've experienced all of those first hand, some of them quite repeatedly).

> Now I wonder why a QR code couldn't work without an internet connection just the same.

Because a QR code is just a short piece of information to tell your banking app who to send funds to - it's like putting a mailto: link on a website rather than asking people to re-type your email address to contact you.