I suppose its alot like fighting on the ground, if i plug some guy two times in the chest with my m4, and another guy shoots him in the head with his m4, i doubt i would turn to him and say "you took MY kill!" more like "dang, good shot!, you alright?".
This is a game, in that.. every one's concerned with "score". In war, and battle you just want to get home alive, and probably would not care too much for someone shooting down the same A/C you shot at. not to say some greedy "aces" like bong and yeager would not get butt hurt to the ability of boasting about killing a few more "enemy". Most servicemen would be happy just to get feet back on land, and couldn't give a dang about kills or score when it comes to bangin' the wife back home one more time.

Shucks.