When a Marine fights its typically not a surprise. They are looking for dangerous people, and they typically find them. If the wrong person gets killed, their wellbeing is not jeopardized. It is strictly kill or be killed. They also have a team, and have an idea of what they will encounter. If in doubt, they can default to shoot. I think using a visible light for them is more dangerous, not because of giving away position, but for alerting of their presence.
You and I will typically be defending ourselves from an unknown threat. If we kill the wrong person, we could easily be financially and socially ruined (sometimes even if we do kill the right person too). Pretty sure that marine overseas isn't going to accidentally shoot his child, but there is a good possibility of you or I doing just that if we can't identify the target.
Military tactics and civilian tactics are typically very different. Have you ever gone out of your way to avoid a sketchy dude on the street? That is a tactic, just like tossing a grenade through a door.
