1) police officer or the security guard of a particular bank. - To me, this is the most logical explanation because anyone who works at a particular bank will still be inside the bank even after it is closed due to the end of office hour. They still need to finalize some accounts, documents and all. Therefore, the only person outside the bank who can still communicate with clients is most probably the guard. Plus I had been in this situation where I came late to a bank that it almost closed. By the time I arrived, the guard said this line to me.
2) a taxi driver or a steward/stewardess - I think, this line is rather formal, so any car driver like our parent would most probably not using this line towards us. Instead, they will be like "fasten your seat belts, will you?" or "honey, how many times have I told you to fasten your seat belts?"
well, those are just my personal opinions though. it still can be wrong. it is not 100% right, but that is all I could come up with.