Knowing who went to or from a single location at around the same time would be super interesting for counter-terrorism. Of course, the intelligent terrorist would pay with cash, which means no Uber except in India, Southeast Asia, and a few others [1].
Which raises real questions, since taxis in some regions have cameras but Uber cars may not.
They already do this, that is track all the locations of cell phones to see if there are two people that "magically" happen to travel somewhere together in unusual pattern. Example I saw was two people at random times "happening" to get on the same mass transit system.
Which raises real questions, since taxis in some regions have cameras but Uber cars may not.
[1] http://techcrunch.com/2016/02/08/uber-begins-to-see-the-payo...