This is one of the most common concerns that clients tell us when they want to use drones for inspection purpose; especially in a residential area. 

The main difference between a drone and a person on a gondola outside your window is probably a recording device. The drone has a camera that can store a digital copy of what it "sees" whereby a person does not. Occupants therefore might feel that a drone is more intrusive than a person. Moreover, there's something about a camera that makes a person feel uneasy. 

I believe society will get past this as drones become increasingly common and especially, when the benefits of drones become more obvious.

In the meantime, certain rules can be in place to ensure privacy of occupants are respected even if drones are used. For example, a rule can be that no photographs/videos of windows should be taken and stored. Another rule can be residents should be given ample notice before such inspection takes place. 

In the end, I believe technology will be able to solve this problem as well. The rules that I have mentioned above can actually be guaranteed by using software, preventing the operation of the camera when it is detected pointing into a window perhaps, instead of relying on the human operator to obey these rules.