That would be a good point, if that actually happened, but Japanese traffic lights have a mixture of green for go and blue for go (with most of them being green).
That the color region that word encompasses doesn't match that of the English words "green" doesn't really matter, and is not particularly mysterious.
> “In 1973, the government mandated through a cabinet order that traffic lights use the bluest shade of green possible—still technically green, but noticeably blue enough to justifiably continue using the ao nomenclature,” Allan Richarz writes for Atlas Obscura.
There is another one to the right as well. They look very blue when turned off, but cyan/green when turned on.