Earlier quoted context omitted.
The ID card allows age verification without disclosing the identity to the service which needs the age verified.
You don't think that the digital ID provider is keeping logs of which sites requested to verify which users? Even government websites are not exactly known for their high security.
Briefly, when the ID provider issues the ID it gets cryptographically bound to your phone. When you use the ID to prove something to a site (age, citizenship, etc) the is done by using a zero-knowledge proof based protocol that allows your phone to prove to the site (1) that you have an ID issued by your ID provider, (2) that ID is bound to your phone, (3) the phone is unlocked, and (4) the thing you are claiming (age, citizenship, etc) matches what the ID says. This protocol does not convey any other information from or about your ID to the site.