Wow, $10 for not turning up. No wonder they can fund legal cases all over the world.
In fact the driver had to have showed up, otherwise he wouldn't have been allocated the cancellation fee. It is determined automatically by the car's location getting close enough to the pickup location to trigger the "your driver has arrived" message, and (for the driver) a "Start trip" button appears. Ten minutes must elapse between the driver arriving at the pickup point and cancelling the job for the fee to be payable.
Often there is a discrepancy between the pickup point and the passenger's actual location. Sometimes it is a drunk taking a fat-fingered stab at where he thinks he is, sometimes it is GPS error. Tall buildings blocking or reflecting GPS signals (such as Manhattan or Sydney CBD) will often put the pickup point a block or so away.
Or sometimes it is the passenger's fault, unable to see the car. The passenger will be given the car's numberplate, but the driver has no idea what his passenger looks like. Maybe they are inside still doing the final packing or whatever, rather than waiting on the street. I once parked at a suburban shopping centre, and shortly received a "ping" from a passenger waiting to be picked up. The pickup location was only a few metres away in a bar. Nobody came out to get in my car, even though I was right there. Perhaps they were expecting a car to drive up. Perhaps they were too lazy to look out the window. I don't know.
In any case, there are ten minutes for the passenger to text or call the driver to work out the correct pickup point. Sometimes I'll get a text before I arrive, specifying the place, sometimes when it's obvious that the car and passenger are not colocated I'll get a text or a call.
I generally give the passenger five minutes, then send a text specifying the place where I'm waiting, At eight minutes I'll send another, warning that I can't wait forever.
I'll do my best to make contact, but if the passenger isn't at the pickup point on my GPS map after ten minutes and hasn't made any effort, then I reckon I'm justified in getting the ten bucks.