The fact is that none of us were there to witness the events in Afganistan or in Derry 30 odd years ago; all we can do is listen to the story as told by both sides and make a decision who we believe. What we shouldn't do is jump to opinions based on nothing more than long held prejudices.
The evidence I've heard so far from Afganistan seems to suggest that in this case some young squaddies did get trigger happy, but we need to wait and hear the result of the investigation that is underway.
As to Derry, I've heard contradicting evidence from both sides, but only it seems from people with a political axe to grind. Both sides so distrust the other that whatever is said by one the other will deny, so I doubt we'll ever know the truth of what happened that Sunday. Personally I suspect that both sides are guilty of covering up the facts they don't want to hear.

Scott