For those interested on the question of age verification and GNU/Linux: be aware that Systemd v261-rc1 was recently released. It now implements an optional birth date field in the JSON user database (see second item under “Other changes”).
The implementation of this field was prompted by age-verification or -attestation laws.
What you quote is the justification why a new field should be added. You can’t just say e.g. a Wardrobe number should be added without justifying it, otherwise it won’t be accepted. You can say a Wardrobe number should be added because recent scientific developments suggest that some wardrobes open up new worlds, so it became necessary to extend the address field.
This doesn’t mean systemd would enforce anything or go into the politics of certain jurisdictions. It just enables distros to use this field, and it’s up to the distros what they want to do with it.