Pickpockets usually don't carry freezers or lead boxes on their person. By the time they are home and can drain the phone, their closest WiFi access points woul

Pickpockets usually don't carry freezers or lead boxes on their person. By the time they are home and can drain the phone, their closest WiFi access points would have pinpointed them. (Though a sophisticated thief might have a lightweight faraday cage on them - sleeve lined with aluminium foil might sufficiently dampen Wifi/GPS/cell signals.)