In North America and Europe, tap to pay was implemented prior to smartphones that could scan QR codes being ubiquitous. Most of us have had cards that support NFC payments for longer than we have had a phone that can read QR codes so it made sense for phones to pick up the technology that worked with the terminals businesses already had than try to implement a new system.

The QR code thing is primarily a Chinese solution to the payment problem (all other Asian countries I've been to have widespread NFC acceptance). Payment cards were never widespread within China the way they are in other places, until AliPay and WeChat Pay became a thing people still primarily used cash for their daily communications. If businesses don't already have credit card terminals but people have smartphones then the QR code starts to make more sense.

One interesting thing about this is that even before North America was widely using NFC payments, people in Hong Kong were using their Octopus transit cards as contactless payment at all kinds of businesses throughout the city. Yet that technology didn't seems to make it into Mainland China.