I've seen a mobile version of this in the flesh.
Really good idea for managing devices over a wide area but not so large than regular networks would be preferable.
A good example was for music festivals, hand all vendors their own sims so they can accept card payments on a dedicated network, run video/audio over dedicated networks. All on some that won't be completely borked because of abit of rain or having the APs saturated because different vendors are trying to use WiFi for other none transaction data.