I imagine that IFI designed the LED to include green and yellow just in case FIRST has four alliances again.
The rookies may not be aware of this but a few years ago (2001 I think, don't quote me) there were green and yellow alliances in addition to the red and blue. At that time the LEDs didn't exist. We used the revolving lights and had green, blue, red and yellow lenses to swap out depending on what alliance you were on.
I don't know why they would turn white though, I've never heard of any robots willingly surrendering during a match yet!
