> What would be the incentive to develop such an app in decentralized fashion? What if there are problems between rider and driver, who will act as a middleman to resolve issues? What about basic support etc?

Sorry if I wasn’t clear enough, but I am precisely talking about this: using the blockchain for what it is good at today, instead of trying to put everything on a decentralized system (which is really hard or just impossible for now).

Uber / Lyft and others have a reputation system in place, opaque and developed specifically for their product. It’s an important part, but it is just a brick in the complexity of the services they are building.

I am talking about replacing this brick by an open, blockchain-based reputation service (that doesn’t exist AFAIK). That way, any app developer could benefit from the transparency and guaranteed properties from the blockchain. It could even be easier to use than to implement it as a private system.