The Reason Behind Countries with Outside-the-Room Bathroom Light Switches. Why do some bathrooms have an outside-the-room light switch? What makes it different from the inside light switch? When you use a public restroom, you probably don't want to produce any illumination that would let other people know that you're in there. This can be helpful if you're in a crowded public space and don't want to disturb the people around you. The only problem is that if there's no outside switch, finding your way out of the bathroom can be difficult because the...