It's not about age verification but control and digital id.

Doesn't everyone have a digital ID already?

My passport has biometrics, the government knows everything about me already through the tax system which is "digital". All my other interactions with the government are through digital services.

What exactly would a digital ID allow a government to do that it can't already? Apart from solve all the issues with having to provide scans of (my already digital) ID documents to every bank/solicitor/mortgage broker/estate agent/etc i interact with, where in many my personal ID documents probably sit on a company file share or some random persons One Drive.

A government digital ID with a one-time code to complete verification would solve all of this nonsense.

On control, again, what possible super power would a "digital ID" give a government that it doesn’t have already to control you?