I find indicator lights, if they only have the purpose of conveying something that's already obvious in some other way (e.g. "the computer is on"-led plus a monitor that's clearly saying it is) fairly useless. I'm glad that most devices nowadays don't have them and are completely dark even when they're on.
And to your comment about cars, it seems to be more about pedestrians that can know about an oncoming vehicle and less about whether the user thinks it's running. The latter seems to be something that can be easily fixed.
