I don’t get drones, they are useful for short duration photography, they could drop things over a short range but duration is too short to go much beyond the boundary of an average town. When it returns to the parcels base in that town for a reloading and battery change, it all sounds complicated to me and as for transplantation organs there is usually no great rush as they are packed in ice and a motorcycle outrider deliver quickly.
Commercial drones are going to be regulated for airworthiness and could be quite expensive to operate compared to delivery vans, Amazon pay less than £1 to deliver a parcel in the U.K. hard to see a saving.