What a crock! Parents actually getting to decide could be trivially accomplished by a first-boot date of birth prompt, at which time the device goes into ‘child mode’ until the date that birthdate becomes the age of majority. Undoing that (say to repurpose the device for an adult) should require the parent who set it up to also do the wiping, much as existing “iCloud Lock” etc requires the owner’s consent to reset.
If a kid is old enough to buy their own phone or whatever and lie that they’re an adult… I’m not that worried about it. Teens have enjoyed sneaking into R-rated movies and raiding Dad’s Penthouse Magazine collection for generations. It’s fine.
Now, whatever this BS is… this has nothing to do with parents deciding.