Knowingly or unknowingly chosen, it is also the colour which the human eye, even those with a slight colour deficiency, can detect against a low contrast background better than red. Some years ago ocean life jackets etc were changed from red to orange to accommodate increased detection/rescue at sea by colour defective observers. The colour the normal human eye is actually most sensitive to is 555nm which is very close to chartreuse but of course that would be of little use at sea as a safety colour to a colour defective.


Regards
Mike