Different states, countries, and multi-country organizations that have legislated in this area or are working on legislating in this area have went with many different approaches. These differ in their scope, how age is verified (or even if age is actually verified), what documentation is required (or even if documentation is required), whether they apply to the web or to apps or to both, whether they make anonymous use harder or not, how much if any sensitive information they disclose to the apps/sites that need to check age, whether they could allow government to track your usage, and in other ways.
Most ridiculous are the comments that after saying how bad it is (clearly talking about things not in the California law) then say how it should work and describe something close to the California law.