The two domestic helpers at the next table in a McDonald’s were chatting in Cantonese. Out of curiosity I asked them where they were from. It turns out one of them is Filipino but she can speak Cantonese. The other is from Indonesia but can’t speak English.
When we talk about a common language of communication for people from different L1 backgrounds, we usually think of English. That’s why I felt a bit flattered that Cantonese became the common language for the two ladies!