Not necessarily. When a new address comes up, a human operator might takes a look at a satellite image of the address and give the drone an appropriate location to land on the property. That data would then be stored. 15 seconds with a human, one time only, is all it would take to make this easy in most neighborhoods.
What about navigating TFRs? Class B airspace? What about failures of the rotors whilst flying over heavily populated areas? Will these things be equipped with TCAS to avoid oncoming traffic? What happens if the path-finding algorithm to get from Amazon's warehouse to your house goes batshit insane and flies it in the approach path to LAX? Who files the flight plan for each of these things?
To quote Steve Yegge, "people will die... if it's YOU... you're going to be really pissed off." [0]
[0] http://steve-yegge.blogspot.co.uk/2009/04/have-you-ever-lega...
The shop.
The post office.
Organising something like this in a controlled area like a campus must be a few orders of magnitude simpler than organising something like this across the US.
it is a fantastic use of technology, I genuinely hope amazon manages to deliver.