Jeeps, like armored cars, scout cars, etc have crews. I assume that the crew of a scout vehicle has been trained on observations techniques and has practiced those techniques until they are better at them then the average GI.
Sort of like why in the game a crew has to remount it's own vehicle, or why a rifle squad cannot grab the Sagger left laying on the ground after it's crew got mowed down several turns ago.
Scouting is a skill set, an MOS, 19D according to this;
http://usmilitary.about.com/od/enlistedjobs/a/19d.htm