
Louis P. answered 11/29/20
MA in Applied Linguistics, and experience in teaching Semantics.
Interesting question. American English has become the international language for a variety of reasons.
For one thing our GI's spread the language as they fought their way through Europe. Everybody loved the conquering Yanks as they freed the captive countries. After the war we brought the Marshall Plan to rebuild the European continent.
Another reason is the spread of the internet where much of the content is in English. I had a Mexican student in my ESL class who had an advanced degree in Mechanical Engineering from a Mexican university but felt he needed to upgrade his English language skills.
During one of my Fulbright gigs in a university in Minsk, I ran across a group of students having a conversation in fluent, unaccented American English. When I approached them to say how glad I was to see Americans studying there, they laughed heartily as they told me that they were from four different countries. I remember when French was the lingua franca but that is a long time ago. Now that it's American English it makes my travels much easier.