Could you emit a virtual credit card for them that you then cancel after the verification is done?
What "unfucking" looks like though? The law is mandated in the UK. What other way of age verification would work better for them?
If a passport isn't working then their age verification is broken, full stop.
Phones can read biometric information from passports and identity cards just fine. Why didn't you think of a personal ID document as the first step to prove ID?
That is a possibility but it's a stupid verification method as not everyone has credit cards. It's just cheap for the vendor.
Unfucking looks like a "look what the UK government policy is causing" PR disaster and a rollback and consultation.
Edit: I suspect this might happen when MPs start getting upgraded...