This isn’t about kids at all. The ID requirement is the WHOLE POINT.
That it is technically possible to do age verification in a privacy-preserving way is thus entirely irrelevant.
They want all online activity tied to ID so they can violently, illegally retaliate in the dark of night against protected expression online that they don’t like.
That’s all this is. Privacy-preserving techniques are irrelevant because they do not accomplish this goal.