Even the 'westernised' chinese didn't speak in english to each others. My father and grandma spoke perfect mandarin and they were not typical.
I once teasingly asked a female english teacher to explain to me "By my head or maidenhead" (a passage from Romeo&Juliet) and she had no f**king(literally) idea what 'maidenhead' means.
--Look obviously the locality-origin composition of chinese in USA have changed drastically in the last 3 decades