Where is the problem with this?
The problem rather is that the user did not create a private backup of the data that he wants to keep.
Once the child is over 16, they can add all their real-world friends again.
(Disclaimer: I'm so old that at 16 I didn't ever had email. Please don't delete all my old stuff.)
https://allowe.com/games/larry/tips-manuals/lsl1-age-quiz.ht...
Edit: Added link
Less good, more fun. To 'prove' that you were over 18 you had answer a series of multiple choice questions [1] about pop culture that most kids almost certainly wouldn't know. Pre internet, finding the answer was surprisingly hard without asking an adult. The main result was that 10 year old me knew a surprisingly large number of obscure facts of about US culture, like who Spiro Agnew was and that Ronald Reagan once starred in a movie with a monkey.
Eventually we found out that you could press some magic key combination to skip the question all together.
[1] https://allowe.com/games/larry/tips-manuals/lsl1-age-quiz.ht...
That's unexpectedly sane from a law like this. Hopefully they can figure out some zero-knowledge proof of age. (But then there's nothing stopping adults from creating and selling proof values to kids.)
That's also true for alcohol and tobacco.
* It is illegal for a platform to provide children with a social media account, not for the child to create an account. Circumvention of this by the child is not illegal.
* No grandfathering - all accounts under 16 once this takes effect (which won't be until this time next year at earliest) must be deactivated.
* Maximum fine (per instance?) is 50 million AUD (about 32 million USD)
* The legislation is vague on the technical details, although it does specifically mandate that platforms cannot use government-issued ID of any kind (including digital ID).