I've used Uber in NY, CA, and FL in the past 6 months. Every time I've done so I was shown exactly the price that I would pay up front. It's a static price. I pay that amount to go from X to Y, regardless of minutes, miles or extraordinary circumstances.
I have no idea what the driver's compensation is based on but it isn't transparently obvious to me that it would be fraudulent for Uber to offer me a static fare that, over the course of the ride, turns out to be different to the value of that ride to the driver.
Imagine: When I am offered a fare based on expected traffic that doesn't materialize, the miles+minutes value to the driver is well under what I paid. Other times, when I hit unexpected traffic, I pay Uber less than they pay the driver because of the extra minutes.
I'm not saying "this wasn't fraud". I'm saying, "I can imagine a pricing and reward scheme by which it's not." If at some point Uber said to drivers "We take an x% cut of the fare.", then yes, it seems clear that drivers would be defrauded by the scheme. Maybe we'll get to find out :).
edit: Other comments have links indicating that my "x% of fare" idea may, in fact, be in Uber's contract with drivers.
If the price is an estimate, and the estimate is revised based upon actual time and distance, then that is within reason.
That said, this problem would be much more tractable if the drivers were employees of Uber. Perhaps that's what should be done? :)