Phones / Tablets - What child under 16 is on their own phone plan? I would be surprised if the mobile providers don’t have controls where you can turn the data off.

I could have gotten a tracphone as a kid if I’d really wanted to, I assume motivated kids today could do the same. It’s expensive, but if a kid gets $60 for Christmas, they can afford a prepaid SIM and lots of people give away or sell old smartphones for cheap. Even more leave them somewhere a kid has access to without regularly checking that they’re still there.