I've used Uber several times, and they pricing works like this:
- Different cities have different pricing, you can go to https://www.uber.com/cities to find your city's prices.
- Uber also offers a number of services. The cheapest is UberX
- There's a base fare (usually a couple of $)
- Then you add a rate per mile.
- And any time that is "idle" - when the car isn't moving - is charged at a different (lower) rate.
The reason for having a per mile AND a idle time charge is that you pay slightly less for sitting in traffic, but the driver still gets paid (whereas per mile would mean he wouldn't get anything).
So if you ask me, it's a fair way of charging.
The app also has a fare estimator, so you can work out roughly how long much it will cost. What's really clever is the app also takes into consideration current traffic!