And with either type of device there is risk of people getting too close to it out of ignorance.
Rotors of some helicopters are low in front - S76 for example, you do not approach from the front, and from the sides you have to keep your head down.
And the UAV’s little rotors can bite, as the guy who tried to demonstrate his in a parking lot near a prison found out when he tried to grab it to hold it down and turn it off.