Don't mobile devices store their battery usage over time (and also the per-app breakdown of energy usage)? I don't know what precision the stored data is in, bu

Don't mobile devices store their battery usage over time (and also the per-app breakdown of energy usage)? I don't know what precision the stored data is in, but if it's precise enough, you could reconstruct past movements using it. E.g. when you arrive into a country, the border control could "track" your steps back for a day or so.