Amazon drones

It seems Amazon are planning to use drones (unnamed aircraft) to deliver your parcels, while sounding like a good idea to the finance department, it really needs thinking through properly.
First off there's the slight risk these drones would hit real aircraft, and although unlikely it's still a factor.  Then theres the much bigger risk of them crashing on cars or busses causing a serious accident, with todays congested roads a very real danger. 
By far the biggest problem though is the problem of delivering the goods.  My street has big trees and lots of overhead wires, all a risk to a low flying drone, then what happens if it manages to find the right garden, theres washing lines, trees, etc, even if it dodges those it can't just leave the parcel on the lawn. 
You see most normal houses don't have closed in gardens, and even those with them often have a dog that wil eat the parcel (or drone) that is if the neighbours or a passer bye doesn't steal it first.
Sorry Amazon, your trying to be too clever, it simply wont work in practice, many people won't get their parcels, and sooner or later some clever bugger will work out they can bring the drone down with an airgun or something and steal the goods, if you don't cause a big accident first.  Stop now while your ahead.