Uber can look at Your address book and track You even when You are not on an Uber ride. Why would they have that right? Because they asked You for the permission to do so and since You want to save a few dollars by using Uber, You agreed. You probably didn’t know what You agreed to, all You knew is You wanted to catch a ride with Uber.
According to Bloomberg, Uber retains permission to hand over data to third parties. If a rider is using Uber for Business, the startup can turn over data to the rider’s employer.