Doesn't sound like the kind of device that your average schoolkid has in their pocket?

Are you the Sisyphus of goalposts or something?

I am willing to be educated; does the average schoolkid carry such a device?

I suspect that the number of kids using not using an app on a device that is aware of its locality is a rounding error.

Tesco* phones on some network's family plan must be 95th percentile.

(* other high street retailers are available)

> I am willing to be educated; does the average schoolkid carry such a device?

Yes.

On at least Android phones, and I'm pretty sure also on iOS, location access is a user-controlled permission that's not necessarily granted to any given app. There always leaks, but are you going to require commercial software to play cat-and-mouse games to get around system security settings?

And some, possibly most, "social media" can also be used without apps.