No idea, more and more common for Europeans to use American spellings. I think some, genuinely do not realise there is a difference and it's becoming commoner for kids in ther UK to make the same error.
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I actually generally find British spelling more elegant, with few exceptions. I generally don't use it, though, as I feel it makes a non-Brit look a bit of a poser. That aside, though, at this point "American" english has effectively become "international" english, for better or for worse. So it's not surprising that international projects or things that target international audiences increasingly use "international" spelling. I've seen it in other areas as well. Being a Spanish company, I don't see that they have any particular reason to use British english, and it doesn't really effect my life in the least, but I am generally not a fan of loss of character / loss of diversity in languages.