Comment The main problem: they don't make sense (Score 2, Insightful) 215
The main problem is the overall uneconomical and generally nonsensical idea of using delivery drones. Trucks are simple and work well in bad weather. There's a huge non-employed workforce of people who can easily be trained to deliver packages. Delivery trucks can be powered by natural gas, which is so abundant that many oil rigs simply burn it off rather than going to the trouble of capturing it.
in the general case, delivery drones don't work. Trucks do.