I've also worked in a good many of the non G20 countries across the planet (geophysical field work) and while, yes, of course skin colour is referred to everywhere it's noticeably less frequent in many countries - I took the stance that the GP was commenting on a relative frequency as compared to (say) the US.

In my experience, which may differ to yours, it was as common in Benin to refer to someone as black as it was in Zurich to call another white.

Thank you. Suggesting that people never used the the term black would imply that I can overhear every conversation. So obviously I can't rule out that the term is used. I just haven't heard it. or, to be fair, I don't remember having heard it. The fact that English is not the majority language in most places is obviously also a factor. And maybe I just haven't been talking to people enough yet.