The imagined benefit of the drones was that some people who didn't care at all about costs but wanted intimidate gratification (and who lived near an Amazon warehouse) would supposedly pay an outrageous fee to get their little order delivered quickly by drone. Quickly meaning in the next few hours, and definitely today. You can already pay an exorbitant fee for next day delivery if your a rich prick who thinks that they need their Amazon toy tomorrow rather than today. It would be pointless to pay more for drone delivery and then wait for the truck to be loaded tomorrow and drive to your neighborhood (perhaps late in the afternoon by the time it gets to your neighborhood) and then risk the complications of drone delivery just to claim that it was delivered by drone rather than by the smuck in the truck. Similarly, we're a long way from having it be economically practical to drive to a neighborhood and then deploy the drone rather than just have the driver punt the fragile package to the door himself. And we've seen plenty of evidence lately that the UPS and FedEX drivers are quite capable of abusing fragile shipments all by them selves without the help of a drone.
Quite frankly, a "Delivered today by an Uber driver" plan makes a lot more sense and is much more economically feasible than delivering by drone (via truck) tomorrow. And in the long run, delivered by a self driving vehicle makes more sense than delivery by drone. A self driving vehicle could drive up to my house as well or better than the UPS man can do today, and I don't have to worry about providing a drone landing pad or other drone related issues.
This discussion in no way should be taken as an indication that I ever believed Amazon was serious about drone delivery.