A drone is designed for un-manned flight, nothing more or less. Sure you can strap weapons to it and use it to make it easier to kill people, but you can do the same with a car. But you can also strap cameras and sensors to a drone and use them to do neat science (like these people: http://espo.nasa.gov/missions/hs3/)
Please don't misunderstand me: Weapons are bad. But if we can't avoid them then it is better to use the best option to make bad things a little better.
My point is that if it can be used to kill a person, then I am not fussed. The fact that it is intended to kill people, then I am fussed.
A car is not inherently designed to kill people. A drone is.