So how many rooftops in the US have an electrical outlet?
Those with a patio or deck up there might.
During kite festival in India, people spend many hours up on the roof. Some number of them will have either an outlet or the just run an extension cord up there. Presumably during the essentially similar fest in Islamabad, where they also fly from the rooftops, there will also be, on at least some roofs, provisions for electricity. At the very least, this would not surprise me at all.
... but wouldn't he be aware of the kite festival there?
It would be nearly impossible for anybody in Islamabad not to know about the kite festival. It would be like somebody in, say, New York not knowing about Christmas. It's a big deal.
But I really want to stress how unlikely it is that this would be a kite of the sort flown at the festival. They are, by intent, not stable. They tend to spin/circle in place until the pilot pulls sharply on the line which causes them to move rapidly forward in a more-or-less straight line. The festival is for fighter kites, they do not dwell in place for minutes at a time, much less the claimed two hours. (The engineering of that is ingenious, but off topic here.)
Finally, that is extremely high up. The line would be very long.
Yep, the less so if the kite was smaller, more so if it were larger, of course. To be that stable in an urban environment, it is going to have to be pretty high to get into clear winds.
Any kite experts out there that would be able to confirm if kite flying at this height is common? I wish we had some measurements to compare.
Well, since you asked, yeah, lots of folks fly their kites up to the point where you can barely see it. For them, that's the point, "Look how high it is!" I like to keep mine lower where you can see them clearly, but that's not universal by any means.
i didnt know he was on the roof until i did the research for you.
To confirm, during kite events in that part of the world, flying from the rooftop during the ,kite festival is most definitely a thing. Every year, some number of people fall off the roof while running around to maneuver their kite. (The festivals are for fighter kites, darting around and cutting down other kites is the game. The cutting-string they used, called manjha, is very thin and coated with a sandpapery-textured ground glass, and winds up draped all over the place and is a serious menace to birds, cyclists, children running around, etc. This dangerous residue from the festival, along with the folks who die falling off a roof, is why the fighter-kite festivals are now banned in some places.