It's a classic prisoner's dilemma, Schatzi. If everybody allows everybody else who is smoking, out of ammo, or our of fuel return to base, then the one person who is willing to pretend to be out of ammo or fuel gains a huge tactical advantage against the others. Naturally everybody realizes this fact, so everybody has an incentive to lie about being out of fuel or ammo to survive when the going gets tough, and pretty soon you have lots of hurt feelings when people who lie to those being nice to them shoot them down when least expected.
Be nice if you like, but realize that the social politics of the game really do not reward that sort of behavior. Thus we would rarely expect to observe it.
-- Todd/Leviathn