I wonder why mostly people are going English-American. There is other English as well. Just thinking.
Shading a little bit off-topic, but there are notable exceptions.
A number of years ago, Canadian newspapers tried to unofficially adopt the Chicago Book of Style. There was such discontent expressed by customers that the newspapers quickly switched back to British style.
As a result we have colourful neighbours who labour for favour attending the theatre centre editting, instead of colorful neighbors who labor for favor attending the theater center editing.
Unfortunately, most spell checking software out there only recognizes Chicago Book of Style and not the proper British style, so that as I am typing, the British forms on the left are all marked by by the spell-checker while those on the right are not. Thus, much of the Americanising of the English language is due to American bias in software.
As was mentioned before, there's English, and there's bad English (just kidding

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I sometimes have to churn out technical documents, where the distinctions become quite important when aiming the documents at either American customers or U.K./E.U. customers. Lessee, should this be "randomising" or "randomizing"?