Regardless of the legal enforceability of these rules, I do think Amazon and the FAA need to be certain that a swarm of package-delivering drones don't cause, say, a passenger airplane crash or the failure of an airport's air traffic control system, before we see general deployment of these drones.

I suspect the true difficult technical challenge here will be upgrading the planes and airports to handle hundreds of little drones flying around, with the legal framework to follow.