In class G airspace (below 1200') in most places, as long as you can fly at a speed and height to avoid hitting anything you are legal. Also see FAR 91.119(d) where it says, "Helicopters may be operated at less than the minimums prescribed in paras (b) and (c) of this section if the operation is conducted without hazard to persons or property on the surface". (b) refers to congested areas and 1,000' above the highest obstacle and 2,000' horizontally and (c) other than congested areas and 500' above person, vessels, vehicles or structures.
That is where the authority to fly single engined helicopters over congested areas comes from. I don't see a problem with it. The stats don't indicate to me that it is dangerous per se.
Regards,
Chopperpilot 47