"But there is an obvious solution: mandate the operating systems (iOS and Android) to share device users' ages when they download apps from the app stores – data the operating systems get as part of the hardware acquisition already. This would be a simple one-step way for parents to control all the different apps that their kids use (in the US, the average teen uses forty different apps per month) and would remedy the fractured app-by-app approach we have today. We should make a societal judgement about whether to set these age limits for smartphones or social media
use at thirteen, fourteen, fifteen or sixteen, then write it into law." in How to Save the Internet by Nick Clegg
Everything else aside, this naive belief system is right up there with "10 Myths every programmer should know about X" where X is email addresses, legal names, postal addresses, dates, timestamps, etc.
Or perhaps they are envisioning a "hardware acquisition" process where the purchaser is forced to take some oath and sign an attestation about all future users of the device...
I think it’s more about setting a norm and precedent that “Age verification is not our responsibility; the App Store layer does that and it’s an established truth now”.
Which itself conveniently helps as a defence in lawsuits when a teenager kills themselves over harmful content etc.