‘Documentation’ was not always as cheap as it is today. If it takes hours to engrave a few words in a stone board or if a single page of paper is worth more than a simple meal, you think twice about what you ‘document’. Chances are that such common practices were considered that obvious that they didn’t need documentation on their own, similarly how you would likely not include ‘plug the computer into a power supply’ when asked to tell a relative how to set up theirs.