Just thinking about what forces might prevent the industry from being disrupted (regardless of whether/how this is good for the public):<p>I think the biggest innovation is the drivers rating the customers. It seems like a joke, but if you think about it, professional car service drivers aren't going to want to pick up just anybody for short rides. That's the real obstacle for scalability among that group. The obstacle for getting all cab drivers to join UberCab is probably the risk of alienating the customer base that might just want town cars, etc., without having to think about the complexity (i.e., it's a software problem, and a pretty easy software problem if done right). The other obstacle is the cost of an iphone, etc., for cab drivers. The obstacles for anybody with a car to join are medallions, licenses, etc., as mentioned. The other obstacle is, even with licenses, the fairness and effectiveness of the rating system is tough. Service history is a mixed blessing. When I step into a cab, I may not actually want to know about the driver's history. I may just want a nearly 100% guaranteed level of service (which theoretically the medallions provide). Though on the other hand it would be crazy to see like average on-time trips, average speeds, customer satisfactions, etc., in one big visual thumbprint before you step into a cab...