This is a big part of the study of anthropology. Every person is assigned roles by their culture and a big part of human culture is learning to perform those roles in the way your culture expects you to. Roles like parent, lawyer, soldier, politician, actor, customer, sales rep, cop, teacher, they all have a set of behaviors and signifiers associated with them. Things like what clothes they wear, how they style their hair and makeup, how they speak, how they behave towards other people, how other people are supposed to behave towards them.

A large part of why this is though, is because it kind of genuinely is not possible for people to actually treat each other as individuals on a moment to moment basis once you've gotten to a particular density of human interaction.

We are still running off of 100,000-year-old hardware, & we have a pretty limited maximum number of people that we can keep track of at any given time. It's a big part of the romanticization of the idea of "Small Town Life".