Winning the Hearts and Minds

Why can't we ever tell who the insurgents are and who they aren't? In yet another case of mistaken identity recently, US forces gunned down 7 Iraqi citizens who were playing a traditional Ramadan game. Or, if you'd prefer to believe the military account, they killed 2 or 3 people who may have been insurgents. In fact, in the words of a Major speaking on behalf of the army, “We were not able to get an accurate assessment.” However, although they were unable to get an accurate assessment, they did know that the people they were attacking were insurgents (the Major also stated that "If some innocents were killed, we regret that,” which I'm sure is much appreciated).