Age attestation (edited) is the law now in California. Noncompliance can mean stiff penalties. If you don't like it, write your Congressman.
To my knowledge they require the OS to have an API for websites and services to access a determination of the age range from.
This is a far cry from the breadth of what a "parental control API" would entail even if it would be part of such a thing.
The way you enable them is by the root user typing a number less than 18.