A long time ago my family and I lived in Belgium for two years. In that small European country there are two main languages: French, which is spoken predominantly in Southern Belgium, and Flemish which is spoken in the north.
What do you think happens when a businessman in the north wants to sell something to a businesswoman in the south? You guessed it: They communicate with each other in English. That seems to suit both parties better.
On a more personal note, when I met my future wife her English was better than my French and so we have always communicated together in English.
So the trend seems to be this: Native English speakers are predominantly monolingual and could not communicate in another language to save themselves. Conversely, non-native English speakers of other languag tend
We have only spoken about business. Of course, the same thing holds true in fields such as education, science, information technology, fashion, etc.
Increased globalisation has led to the need for a language that becomes common ground between speakers of different linguistic backgrounds. Rightly or wrongly, English has become the default language that has been chosen for that purpose.