For years tech companies such as Amazon, Alphabet and Uber have promised us delivery drones bringing goods to our doorsteps in a matter of minutes. So why are they taking so long to arrive?
One word: regulation.
If our skies are to become as crowded as our streets, airspace rules need updating to prevent accidents, terrorist attacks, and related problems, such as noise pollution.
Even with relatively few drones in the skies, the number of potentially dangerous incidents is worryingly high.
Just last month, a “rogue” drone closed Wellington Airport in New Zealand, while a UK drone user was charged with endangering lives by flying too close to a police helicopter.
And Venezuelan President Nicolas Maduro says he was recently the target of a drone “attack”. Regulators are trying to take back control by implementing registration schemes.
First developed for military use during World War One, drones are now a global industry that investment bank Goldman Sachs expects to be worth $100bn (£79bn) by 2020.
Their commercial potential is already being exploited in many parts of the world, albeit on a trial basis.
In Switzerland, the national postal service Swiss Post has started using drones to ferry laboratory samples between hospitals in Lugano and Bern. In China, e-commerce giant JD.com has been sending packages by drone in certain rural areas since last year.