Cellphone service providers will most likely be unwilling to start a contract with a child, so the child can't get a SIM on their own. Also if the parent wants to make sure that the SIM card they get can't be used with another phone than the one they provided, they can get an eSIM.
The child is also not going to have access to their home wifi unless their parents provide the password. That network is also totally in their control. They can setup a firewall.
School networks should also have firewalls, if they even provide wifi to the students which arguably they shouldn't.
The only remaining way to get internet access is through open networks on restaurants, etc.
If the child is old enough to be hanging around outside like that though, they're likely old enough for social media, I think.
Is "no contract" to be taken super-literally? Do they not ask to sign a terms-and-conditions document at least? or ask for ID at least to ensure you're a resident of the jurisdiction? I always thought "no contract" was just a term of the trade to mean "no post-payment contract". I'm skeptical they're willing to have anonymous users.
> Do they not ask to sign a terms-and-conditions document at least?
Not when I got one (… two … no, three…). No idea what current rules are, may have changed, but back when I lived in the UK you'd find stacks of SIMs on supermarket shelves for £0.99 each, no questions asked. Topping them up was also no questions asked.
It's possible there was a tickbox somewhere for "you agree to the T&Cs", that's the kind of thing that I'd not even remember, but no actual signature was needed.
Germany (where I live now) needs a proof of ID to register a SIM, so did Kenya when I visited, but the UK hadn't done anything like that by the time I left the country.
The child is also not going to have access to their home wifi unless their parents provide the password. That network is also totally in their control. They can setup a firewall.
School networks should also have firewalls, if they even provide wifi to the students which arguably they shouldn't.
The only remaining way to get internet access is through open networks on restaurants, etc.
If the child is old enough to be hanging around outside like that though, they're likely old enough for social media, I think.