It's actually about what is supported natively in Web browsers and what the vendors of those browsers have done to make it better.
Sadly you are correct that the mentality of the browser vendors is VERY card (and US) centric so accommodations for other payment methods get very little attention.
This is not a fault of the working group participants who have tried to push for everything from iDEAL to crypto but in the end it's pretty clear we're heading for a wallet-dominated world and we all know who those wallets will come from unless we push back.
Sadly you are correct that the mentality of the browser vendors is VERY card (and US) centric so accommodations for other payment methods get very little attention.
This is not a fault of the working group participants who have tried to push for everything from iDEAL to crypto but in the end it's pretty clear we're heading for a wallet-dominated world and we all know who those wallets will come from unless we push back.