Phones should have a border crossing mode where only basic functions are accessible until the device arrives at a pre-defined location. If the device does not arrive at the pre-defined location by a pre-defined time, family or friends are notified and the device wipes itself. National borders are data-hostile environments.
Discussion
You mean like in iOS parental controls? Wipe your kids phone once and they think twice about their location. It's not full blown geofencing but might have the options you might be looking for.
You can also setup iOS parental controls on yourself to block specific apps for specific times. I believe there are also location settings you can also integrate.