Different languages use different phrasing to express the same level of politeness, formality or familiarity. Directly translating the words from one language to another may result in a sentence at a different (usually unintended) level. This creates the impression that the speakers of a language (usually coinciding with people from a particular country and culture) are all polite or all rude. They simply translate their thought to another language, where the phrasing is above or below the intended level of politeness. This is one way that stereotypes about a nationality’s modesty, assertiveness or formality are created.
As an Estonian in the UK, I was considered rude, because I answered “yes” or “no” instead of “yes, please” or “no, thanks.” In Estonian at the time, “no, thank you” would have been formal or ironic (mockingly formal) and I just translated my ordinary reply to English.
The level of formality in a language changes over time and with social class. A good example is TV series about 19th century Britain, where people say things like “you are too kind, Sir”. In modern times, this would sound strange.