I’m not surprised that the newer traffic lights are green - blue LEDs are more expensive, specially if you’re trying to reach a specific colour. Perhaps the switch prompted legislative organs to stop trying to interpret the old word through the newer, more restrict, meaning.

This reminds me a similar phenomenon in Portuguese - the so-called terra roxa “purple soil”, actually red:

The case is a bit messier as it likely involves calquing another Romance language that kept Latin rossus as “red”; likely Italian (terra rossa). But under-the-hood, it’s the same phenomenon as those Japanese drivers talking about blue traffic lights - a colour word changing meaning, but the fossilised usage still stuck there.