It is generally believed that the poor in ancient times could not afford to go to school and could hardly read. Only some rich people can read, and these poor people don't even have names. They usually use the age of many peers or parents as their names. It's convenient for everyone to call.
We often hear that Zhang San Li Si is not without a source. Their source is the ancient working people at the bottom. Hotel waiters are almost all poor people from humble origins. Everyone has no birthright to say. The boss is the boss, and of course they are "second children". As people say, it is natural that waiters gradually became the names of ancient waiters.
At first, it was not a bartender, but a continuation of people's long-term living habits and ways of speaking, which made people think that waiters were bartenders. Since the Song Dynasty, this name has become popular, so the TV series that everyone watches are basically called shopkeepers.