The crisis caused by e-bike traffic bans in several Chinese cities makes one wonder if new generations of drones might take the place of urban couriers. Visions of some modern futuristic megacity with skies filled high, low and wide with nifty drones delivering South Korean cosmetics, urgent medicines and nanochip upgrades make for a nice place to live.

Yet the e-bike crisis forces us to rethink. It is risky to ride and risky to cross the street. So the net to clean up this semi-organized chaos has severely deterred the couriers who had suddenly become ubiquitous in just the past 15 years.

Seattle-based Amazon revolutionized electronic retailing under the bold inspiration of Jeff Bezos, and is now vigorously promoting drone delivery as a test concept. The principal target is delivery of packages weighing less than 2.2 kilograms within a radius of 15 kilometers. It is claimed this covers 86 percent of Amazon deliveries.