I know a few people involved in drone delivery projects. Their employers are always just about to launch commercial services, and it has been that way for several years. There was to be a big trial of food deliveries within a university campus, but the local aviation regulator stopped it from happening due to a load of unresolved safety issues.

The problem is that drone delivery in urban areas is difficult. Accurate landing issues, noise, kids throwing stones at them, overhead wiring, managing safe landing when there's a fault etc. Oh and the big one, air traffic control. The authorities want drone operators to co-ordinate their flights so that they don't crash in to each other. The clients of the drone operators are obsessed with commercial confidentiality and don't want that to happen.

I'm in Ireland the only type of drone delivery that seems to be successful so far is delivering medicines and the like to small islands off the west coast where most of the above issues don't apply. It seems to me that drone delivery will end up being a niche thing. Ground based robot delivery systems will probably succeed where drones fail.