Yes, the child safety is very necessary. The simplest solution for simplex would be simply the "parental control" like restricting the contacts or allowed groups by checking by the phone number or imei with no client side scanning... However, EU is to force such client side scanning.
As simplex is open source, clones could show up with no restrictions but this can be prevented with the blocks on the google play (parental control) and so on. Of course, you can never solve the issue with completely new phone with the sim card bought on some "homeless" person but there is no bulletproof solutions.
It's worrying trend that EU now chooses the worst solutions for quite long time
How so - even doi links?