There are ways to implement this without affecting anyone's privacy. For example here in Poland everyone has an ID and everyone that wants to use egov services, file taxes, or check their prescriptions online has a cryptographic identity.
It would be trivial to implement a challenge that would work like this:
- the site requests you to sign a challenge
- you sign the challenge and provide it to third party verifier. (can be a gov site or a private company)
- service verifies your signature and gives you the copy of the challenge signed by itself only so your gov ID is never revealed.
- you supply the signed challenge to the original site. You prove you're an adult.
Being Polish and knowing our politics let me tell you how this will go down. The current gov is the one that will swallow everything that comes from the EU (because they are led by a guy that was the deputy leader of the biggest EU parliament party). Same guys that wasted billions trying to implement the e-prescription service that was implemented by the next gov in a fraction of time and cost.
In short they are horribly incompetent on tech so I expect the first version of this will be as bad as the crypto laws they proposed.
But thankfully the president is not from their camp and he will not sign any BS (if it starts looking like he might there will be mass protests - just look up the scale of protests last time they tried to censor the internet)
And then they will be forced to change it.
There is no technical reason why you should disclose your identity to proove you have one. That is the entire point of having those crypto identities. That you can manage how much information you provide.