Let's see:
1) Open banking, where a bank confirms a user is over 18 without sharing any other personal information.
Yes please, I want a MitM attack to be able to sniff out what bank I belong to and my credentials. Yummy,
2) Mobile network operator (MNO) age check, where the responsibility is shunted onto an MNO content restriction filter that can only be removed if the device user can prove to the MNO that they are over 18.
Sounds great. So, apart from the hassle to the MNO, the UK Gov *does* remember that not everyone uses only a mobile device to access the 'net, right?
3) Photo ID matching, where an image of the user is compared to an uploaded document used as proof of age to verify that they are the same person.
And who does the matching? And what if you're on a PC that doesn't have a webcam? Can the kiddies simply hold a photo of Mom/Dad in front of whatever camera is being used?
4) Credit card checks, where a credit card account is checked for validity – in the UK, credit card holders must be over 18.
Yeah! That's what I want! My credit card details spread around the internet to any website that deems that the require it for age checking. How long before a plethora of dodgy sites turn up saying their contents require age confirmation, fork over your details thanks?
5) Digital identity wallets and, our favorite, facial age estimation, where the features of a user's face are analyzed to estimate the user's age.
I don't have a digital wallet, and facial recognition again requires you to have a camera.
Really. I swear it seems like there's a requirement for common sense to be surgically removed before you're allowed to run for office.