And we have quite a few who do not, even with eyewitness accounts. In the 1700's you would have stood on the side of the road scoffing at Paul Revere because "The Red Coats" can't be coming, cause nobody would have so little fashion sense to wear coats of red!
For what it is worth I have seen a dreaded "black helo" from less than 50 feet. Not impressive. I was staring at the pilot, who was staring at me. He lost interest before I did and flew off. Comes from driving where few ever go. Having some military experiences I can tell you that it has no "step here" or other normal markings, it is all black with infra-red resistant paint with no external markings. It was also a very old US model, the pilot was not wearing any identifiable flight suit and there were no guns or interesting pods mounted on the copter. The only antenna I could see was a odd looking v antenna mounted on the lower third of the nose with about an 18 inch array with a about a 30-45 degree divergence.
The existence of "black helo's" is not a tin foil subject in the towns that they are based in, it is a ho-hum... They fly out of the local airport where they have a hanger of their own. Some times when they take off they carry troops without markings on their uniforms. It is hardly a secret that they are UN folks, after all the National Parks are not owned by America any more.
I never worried about it too much, their "secret" base in the backwoods is known about by the US Govt as jolly green giants fly in there about once a week. I got a hankering to see if I could spot their base one evening and got the helo treatment for my troubles. Never did spot the base but I must have been pretty close.
De-Nile ain't just a river in Egypt I see.
While living in Silver City NM I met several people who were familiar with "black helos." Not just backwoods "cranks" either. They are known to the sherriffs, businessmen and city officials. One guy I talked to had an enounter similar to yours. He had a camera and almost got a picture. He did see blue helmets on some of the crew though. They saw him and immediately dropped below a ridge and left.