Uber uses GPS tracking for every ride its drivers give, so the system knows where you are at all times. You hop in and the driver punches the address into his phone for turn-by-turn directions and tracking. If your driver takes you down a dirt road and starts playing his "Dueling Banjos" Pandora station, don't worry. Uber knows where you are. Likewise, if your passenger gives you directions that lead to a dark, dead-end ally of the kind noir films are made of, Uber knows where you are. If you're in a cab, you better have the GPS in your own phone turned on if you want anyone to know where you are. If you're Julian Assange and trying to avoid capture by international police forces, you might want to avoid Uber altogether.