An excellent question indeed.
Noch keine Antwort...
Still remains a mystery to this day.
Its because the co-founder hates green. When designing the logo he told the team that he hated green.
So they thought it would be funny to make Duo green. And the rest is history....
Learnt this off Tim Ferriss' interview with Luis Von Ahn
Er ist grün, weil er grün ist.
Asking the real questions !
Warum ist der Himmel blau?
Weil Duo die Natur liebt.
Weil Duo Vegetarier ist.
duo isst zu viel gemuse
he ate paint
Why's "Why's Duo green" incorrect? It shouldn't be
Ja! Warum ist Duo grün?
It must have been something he ate.
Because of all the money he gets from plus members.