Sure, which is why Uber has invested so much in driver acquisition in expanding it's territories. But once those territories are established they should be able

Sure, which is why Uber has invested so much in driver acquisition in expanding it's territories. But once those territories are established they should be able to spend far less. If driver times start to become longer, it means existing drivers have a higher utilization and will make more money, drawing more drivers to drive for uber, and solving the problem in a virtuous circle.