why didn’t these countries go the NFC route instead of QR codes?

QR code still works when either end is low-tech (paper/wearable/sticker), by using out-of-band means (SMS/soundbox) to confirm the transaction.

Further, NFC is usually the first to be left out when manufacturers cut costs to hit lucrative price points.

Apple never implemented host card emulation (HCE) as an API, but that doesn't matter as these payment systems usually aren't backed by a payment card network, thus they'd have to build needlessly complex reconcilliation systems when transactions already debit directly from accounts, and offline usage isn't considered a major use-case.

Nfc needs a special chip qr code needs just a picture and camera. Makes a huge difference in infrastructure cost. Getting millions of shops to put in nfc terminals compared to get them to print qr codes makes adoption a lot faster

To build on the other comments, because anyone can just print up their QR code. Somchai the Tuk-Tuk driver can simply print the QR code for his personal bank account and glue it to the roof of his Tuk-Tuk and now he accepts electronic payments.

thank you all for replying. i now understand a bit better why they went the QR route.

Some sellers don't have a smartphone/screen and rely on the honesty of the user (they just ask to show them the receipt). I don't know how they manage their wallet though (maybe their kid or a friend?).

The "wallet" is just an ordinary bank account in these cases.