Much has been said about Uber's multiple self-inflicted wounds during a period of very rapid growth and that are now being fixed. The reporting and commentary have tended to cloud the extent to which the company's innovative approach has transformed urban transportation. On a recent trip to London I was vividly reminded of the next stage of this transformation by a traditional London taxi driver.

It is not easy to become a London cabbie. Applicants have to go through four years of training to acquire the legendary knowledge of the city's streets, alleys, twists and turns. They are subject to licensing requirements and a host of regulations. They drive expensive black cabs, which have become icons.

And, these days, they are heavily outnumbered by lightly regulated competitors who go through little training, drive their own cars and rely heavily on technology for client pickups, routes, payments and invoicing.