The reality is in the olden days people rarely travelled and rarely communicated with people outside their immediate area.
You did not need to communicate with many people outside your immediate location
Today the world is much closer and people need to communicate. Because of the internet which was developed in the US and that US and Great Britain were the main business countries so english became the language is business, sort of by default English has become the worlds language.
Airline pilots and traffic controllers are ONLY allowed to speak in english while on the job (So there is no miscommunicaton in the airlines)