Well according to the drivers they aren't getting paid if they aren't driving. So it perhaps motivates them.
EDIT: Thinking about this a bit more what is the value of having nominal control over a fleet of vehicles of various capabilities sitting around a metropolitan area? Someone wants to go from point A to point B? Dispatch a nearby passenger capable vehicle to pick them up and drop them off. Package needs to go from here to there? Send a vehicle and driver over to get this package and take it over.
Imagine the economics of consolidating courier service, taxi cabs, emergency transport, into a single 'app' will all 'contract' labor.
