[KineticLensman]

Green is mentioned a few times. As caseyavila points out, the article is about colours historically used when painting - aka 'subtractive colours' - in which green isn't a primary colour. As per TFA, you can mix a muddy green from blue and yellow or use a specialised green pigment, as they become available historically. In light-based systems (as in screen RGB), green is in contrast a primary colour. Notice that subtractive colour systems (print ink, pigments, etc) often employ a fourth 'key' colour to get true blacks.

On the subject of green as a colour in its own right, the human visual system excels at recognising different shades of green compared with red.