The fact that most people value their freedom and are not looking to commit crimes. There are many many things that could be done, but if done mean essentially destroying your life. Most people don't want to destroy their lives.
Most people don't want to destroy their lives by shooting someone with a gun, yet it happens every day.
My point was that there are people who want to murder, and drones will be very suitable for that, and the fact that 99.99% of people don't won't really matter.