Scooters could be using NFC/RFID payments today (e.g., Apple pay) instead of QR codes. So you could just walk up, tap your phone, and go. UWB offers no real usability advantage here. Scooter companies don't use these methods because they want you to install their app for user retention reasons.
So what's missing in your scooter use case is a loyalty mechanism rather than a lack of payment technology.
Also you want your scooters to work for the large portion of people who didn’t upgrade to a NFC enabled phone yet
QR codes are highly backwards compatible
Doesn’t preclude a NFC improvement, but my experience with Scan QR to Unlock has been very good, point the phone at the bike, bike unlocks, not much to improve
So what's missing in your scooter use case is a loyalty mechanism rather than a lack of payment technology.