Many of us that fly in the mountains enjoy the natural high of flying to the top of a mountain and looking at what's on the other side, or what's on top. If we stay within the 400' AGL limit we all think that's OK, anyway that's what I thought until recently. I've come to the realization that although we have our rules to follow, which we all try our best to comply with, others may not follow their rules to the letter. I'm talking about private airplanes and helicopters. Many of them do not follow their 500' AGL rule to the letter. It's very common for a prop driven airplane, such as a Cessna 172 to struggle getting over higher elevation mountains so they fudge a little and fly over with only a couple hundred feet clearance, mainly because it takes time and fuel to get higher, and they deem it acceptable because as soon as they clear the peak, they are almost immediately above the 500' AGL rule, assuming the mountain is not a mesa plateau that's flat on top. I've had this conversation with 2 avid recreational pilots. Sometimes they enjoy the low flying so see what's on the ground, forgetting about drones being allowed up to 400' AGL. I was recently in Colorado at the continental divide, Loveland Pass to be exact. I was only 150' AGL flying quite easily with my P3P having a great time flying over some peaks of the divide (12,000 ft ASL). Then here comes a helicopter carrying something below it. I couldn't make out what it was, but it was apparent that construction of something was occurring and this was a delivery. I think it was a ski-lift part of some kind. He was very low going over the peak, way lower than 500', likely around 200-250' AGL at the mountain peak. Fortunately I wasn't very close and all was good, lucky for me. Yesterday I saw the same thing over Hi-way 241 in Orange County. There was a commercial helicopter, larger than a news helicopter, flying about 200' AGL over the peak of a mountain, very low. This was only at about 1500' ASL, so it wasn't like the air was thin or anything, he was just flying too low. And he wasn't looking at anything on the ground, this bird was bookin by quite fast. Since private aircraft ALWAYS have the right of way (in my book), regardless if they are breaking the rules or not, I only wanted to make you guys aware of this potential hazard to conflict. Nobody wants an incident that would make drone headlines. So if you're flying to a peak, be careful and listen for other aircraft. As a precaution my AGL is now about 50' on peaks, using visual estimation from the iPad screen. This kind of scenario can be a real issue, we all need to be aware of it, and very careful.