If you're talking about scale: Just build an app which cherry-picks part of the market -- either specific users or specific locations or specific use cases -- a

If you're talking about scale: Just build an app which cherry-picks part of the market -- either specific users or specific locations or specific use cases -- and then fails back to Uber (automatically, or manually) when unavailable. i.e. I could build "the Uber for when you want to go out on a date and impress someone in the car" as an overlay service.