I'm skeptical about delivery drones for this reason. Between the noise, security concerns, and visual pollution it will be hard to implement mass adoption of UAV's for delivery.

I could see delivery drones for last-mile drop offs... imagine delivery trucks as automated machines with a small swarm of drones (4-6) per truck.. the truck drives a route on the main street(s), while the drones do the drop-off to the door.

It could work in that scenario... My biggest thought for drones, is it won't work from the distribution centers, simply because they are too far out from a lot of the drop off locations.. but combined with trucks, you could have the trucks drive less in-out, and drones for drop off. Would need a handler in addition to a driver though, depending on automation capability.

This would also need to be supplemented with uber-like service for deliveries that don't fit well for drone drops.

You can run the motors out of phase to cancel noise.

It doesn't work.