Red and green together are by far the stupidest colours to use for any serious application, and the fact we do so is largely because it is very difficult to make blue with a yellow flamed parrafin lamp (a blue filter just makes a green light).
Anon OpinEverybody knows green means something is on and red means it's off. Blue or white lights could literally mean anything. Manufacturers need to stop using them just because they think they look cool