You're missing the point. Yes, I recieved fire where I couldn't tell which building it was coming from....but what are you going to do? Put a SABLE round through some random houses?
No, we reacted accordingly, maintained cover, switched into bounding overwatch mode, and looked for the guy(s) to screw up and show himself.
If we KNEW which house it was, or if I saw the guy take another shot, I put an AT-4 into it or we'd kick the door in because the guy who leaned out of the window and shot at me just guranteed that his house was now considered hostile. But I can tell you that no one shot into a house that wasn't ID'd as hostile.
One of the harder things to deal with was the fact that guys would cache weapons in a house, shoot at us when we approached. We would react, close in on the house, but by that time they would have slipped out the back, mingled with the running crowd, and locate themselves in another house with another cache. Even in that situation we couldn't very well level a house without ID'ing a muzzle flash or a hostile target.
My point is that it's a dynamic decision making process, it never stops....you can't always say that collateral damage is ok, you can't always say that non-combatant casualties are justified.