Why doesn't the sniper AI soldier I command see enemy targets 200 meters or more away?

After all, that's what snipers are for, right?

Well, one way is to play missions that were designed to give the sniper binoculars. Another way is to issue the sniper a command to watch the specific direction you know the enemy is located in. If either of these alone don't do the trick, move forward a little bit in the direction of the target. This has often caused the detection of the target to be triggered for some reason.