That’s why no one should blindly trust Wikipedia. There’s no evidence for the Japanese “go” light ever having a blue color, the first traffic lights in Japan were imported from the US and the first Japanese traffic law to mention traffic lights called them 緑 (green) not 青 (green or blue depending on the context).
Also, in the US lights used to be a pure green but were updated to be a blue-green so that color blind people could differentiate the green from red. You can still see the original green in some super old lights that haven't been updated.