If you lived on a border of a country that speaks different languages how is it chosen what language you speak? If you lived on the border do you just learn both languages?
Or is it more if you lived even like 500 meters of a border do you learn the language of the country your in? Do people choose it based on nearest popular city to where they’re at?
You realize that speaking a language involves talking to another person, right?? So you speak what the interlocutor speaks in any given situation… and if both parties speak both equally well, then they generally speak a mix of both, based on whim or topic.