I don't understand how Uber works, as I'm not a driver. I assumed you paid an Uber driver to take you from point A to point B for some amount. The driver kept some percent and the rest went to Uber.
How does Uber lose money on this transaction. Or, more to the point, how does Uber lose money on each ride?
The passenger pays the fare in the app, and the driver gets a percentage of the fare. In some instances, Uber will pay the driver more than the fare, otherwise known as ride subsidizing.
This is mostly done to get more drivers into a new market. Uber has a chicken or the egg problem in new markets (like China) so they need to pay a premium to drivers when there are few passengers. They might have to pay a driver $50 per ride because they will only have 2-3 rides per day, even though they only charge $25 per ride to the passenger. In this state there will usually be far more drivers than passengers, so the level of service is excellent. Soon more passengers install Uber in this city, and once drivers can get 10 fares per day their payment per ride can go down to $20. The price per ride can probably go up a little too since they don't have to undercut taxis as much once Uber becomes more ubiquitous.
Uber spent around a billion dollars per year trying to break into the China market this way (plus many other similar strategies and marketing costs).