I'll take a shot at explaining my reason for doing this. I uploaded yesterday a photo of five aircraft in formation over SZP's runway as part of a missing man tribute (there were multiple passover flights-I just uploaded one of the group flight photos in the airport section). Two aircraft were trailing smoke. There were nearly 100 spectators on the ground. To upload this photo in the aircraft section-I would have to pick just one of the N numbers, which would not be fair to the other aircraft, or their pilots. Four of the aircraft were Nanchang China CJ-6As, the other was the solo pass Yakovlev Yak 52.
I put the solo pass photos of N6294D properly in the aircraft section. It would not have been fair or right to put a group of aircraft in flight in the aircraft section. What would you do if you managed to get all the Blue Angels in one photo? Assigning it to the relevant airport only makes sense. I can't speak to other examples unless you cite the photo links, and then the relevant photographer should explain his/her actions-not me.