Japanese is the opposite. You would ask, Gyūnyū ga arimasen ka? (literally, Do you not have milk?) Using the negative form is more indirect and polite, showing that you are prepared for a negative answer.
[T]he local dialect with its heavy Chinese influences may appear brusque or even rude, but saying "You want beer or not?" is in fact more polite in Chinese than asking if you want beer, after all, the person asking you the question is offering you a choice, not making a demand.