Indeed the implementation is important. It is possible to implement it so that the central provider (e.g., whatever state agency issues your driver's license o

Indeed the implementation is important. It is possible to implement it so that the central provider (e.g., whatever state agency issues your driver's license or state ID) can issue you a digital copy of your ID which is cryptographically bound to some secure hardware you own such as a smartphone or a stand-alone security device. When you want to prove your age to a site there are protocols to allow you to prove to the site that you have such a bound ID on your device and that it shows that you are old enough for the site without revealing anything else from your ID to the site. There are such systems currently being tested in the EU as part of their EU Digital Identity Wallet project, which is expected to start becoming available to the public in 2026. Note that the central provider's involvement is just when your ID is issued. They have no idea when, if, or with whom you subsequently use that ID. The sites you use it with only get the age information so even if they are cooperating with the central provider to try to out you they can't provide anything useful. All they can tell the central provider is that someone with an ID that came from that provider and that was over their age threshold visited the site at a particular time. I think the people objecting to age verification really should also as a back up plan try to make it so if age verification is implemented it uses such a scheme.