Well, why does it have to involve privacy? A camera on a marsh with thousands of hours of footage could be useful data (has bird, doesn't have bird? Water level? Cloud cover?)
A tollgate recording vehicle pass-through with a timestamp, a train station gate recording individual pass-through with a timestamp, etc, with huge volume could be useful data.
A tollgate recording vehicle pass-through with a timestamp, a train station gate recording individual pass-through with a timestamp, etc, with huge volume could be useful data.