Have you ever lived in a place that had a doorman? I have not.

What is the purpose of a doorman?

In the show Family with Kristi McNichol, the first episode in season one had one of the daughters living in a place with a doorman.

The Davis Family's building is quite posh, with a very large lobby. Instead of a visitor having to be remotely "buzzed in" by a resident at home in their room, past locked doors (often within a small lobby area), the doorman handles keeping out any stranger who for all intents and purposes is trespassing. Perhaps someone who wants to "crash" on one of the lobby sofas...!

Here are a couple of things I found online:

"An apartment doorman is a building staff member stationed at residential entrances to manage visitor access, assist residents, and monitor building security."

"An apartment doorman or doorkeeper greets and opens the door for residents and their visitors. They also secure package deliveries and deter trespassers. Doormen offer luxury and security, but they are costly and not perfect."