I suspect that communicating a flag value of boolean true/false that "this computer is in use by a minor" from the operating system (via browser or app) to a remote SaaS service like something run by Anthropic will be seen as insufficient by the SaaS, so they'll necessitate ID-scan/live-selfie verification anyways.

Meanwhile, the age flag in the operating system will be used for other forms of authoritarian control. It will have actually accomplished nothing other than limiting peoples' fundamental civil liberties.