Why Hong Kong ppl so rude?

In restaurant everyone shout at the top of their voice

Order food ask to hurry up when I inquire about the dish

Then throw the dish on table

Their life is fast paced but in Japan also fast paced yet polite

Can hear shouting
Lei GAO Chor ah???
Chi seen
Lei ho mo ah??

Worst is they are rude coz i don't speak Cantonese
Speak mandrin they think I'm PRC so then I speak in English but they don't understand?

They think I'm PRC??? How