Absolutely, flying them over the people masses at Burning Man is definitely not a good idea. I operate UAVs commercially in Germany, and both my insurance and f

Absolutely, flying them over the people masses at Burning Man is definitely not a good idea. I operate UAVs commercially in Germany, and both my insurance and flight permit explicitly forbid overflight of people or animals. However, even when not directly overflying people, responsible UAV operators take a number of safety precautions to ensure maximum operational safety of the devices. For example, using an octocopter instead of a quad would allow a motor and/or a propeller (and sometimes even two) to fail in flight without losing control. Another example are GPS-assisted autopilots, that can monitor and enforce safe flight envelope (distance, altitude) and return the aircraft to its starting location in case of radio signal loss or low battery charge.