[nemetroid]

Horizontal lights are not consistent across countries. The linked article has an image of a Japanese horizontal traffic light with red on the right, whereas an American traffic light would have red on the left.

[lozenge]

And some countries don't have horizontal lights at all.

https://youtu.be/sXbHdKJ1D78

[bluGill]

Which is even worse. I grew up in an area with only vertical lights. After several years of driving I ended up in an area with a horizontal light, one end was white and I had no clue if that meant stop or go. (I'm colorblind so I normally think top=stop, bottom=go)

[LeonidasXIV]

I don't think I've ever seen horizontal lights in Europe at all. Fairly common in Japan though.