Subscribers would specify an origin and a destination, and perhaps a few preferences. The app would then function as both journey planner and universal payment platform, knitting everything from driverless cars and nimble little buses to shared bikes and ferries into a single, supple mesh of mobility. Imagine the popular transit planner Citymapper fused to a cycle hire service and a taxi app such as Hailo or Uber, with only one payment required, and the whole thing run as a public utility, and you begin to understand the scale of ambition here.