Because “International Organization for Standardization” would have different acronyms in different languages (IOS in English, OIN in French for Organisation internationale de normalisation), its founders opted for the short form “ISO”. The story goes that ISO is derived from the Greek word “isos”, meaning equal.
Whatever the country, whatever the language, we are always ISO.
Why are they like this?
From their website:
https://www.iso.org/about
A good chunk of the French language is just the English language, in a French accent.
a good chunk of the english language is just the french language, in varying accents.
(a ton of english vocab originates from french) (source)
UNO, ONU, NATO, OTAN
In 5 minutes in Wikipedia I found “UN, ONU, NU, YN, FN, VB, APB, AN, UM, SPB, BMG, ONX” just for the United Nations, and it’s not exhaustive.