There is I agree a privacy and respect issue here, but there is a difference between flying over property and snooping. I mean, I get hot air balloons flying over my house reasonably regularly, often low enough that I can here the gas being fired into the balloon. Do I see it as an invasion of privacy? No is my answer to that. Now to have a drone literally come into down and into my garden, capable of seeing into the house would arose suspicions, and really infuriate me but flying over houses, it really is no greater an invasion of privacy than say Google maps and earth which show people's once very private gardens.