Could your child not just call or text their friends? Or is the real expectation to not have to intervene at all about their preferred platform?

Only if all the other kids are not on social media. When I was in school, birthday parties and such were organised on facebook. If you were not on facebook, you weren't invited.

If everyone was banned from facebook we would have organised them via text messages or email. That's the main point of social media age restrictions, individually banning kids is too punishing on those kids so parents and teachers don't try. Doing it across the whole population is much better.

I think the idea is for the child see their friends in person... not call, text, or internet.

So even if their own child has no phone at all, they have access to the internet through other children's unlimited mobile access.

I'm saying they'll use their friend's devices.