You don't need a perfect fix.

I'm sorry, but if you're threat model is your kid getting a fucking burner phone, I don't know what to tell you.

Even this law won't fix it! Why, couldnt your kid just save up and buy a plane ticket to the US?? Oh no .. we need a global law don't we?

Or, maybe, we throw away that thinking and acknowledge that the problem is not that big and solving 99% of it is MORE than good enough.

Your kid is way more likely to die in a car wreck. Focus on that or something.