Why do they use 3persons/4persons instead of 3people 4people?

Question

I saw the room it says "4persons" for the other room "6persons"

those were priviate rooms in certain famous restaurant.

wonder how's it different between 4persons and 4people

Answer 1

I would say it was a grammatical error on the part of the restaurant. Person is singular, people is plural, so people would have been the correct usage.

It's possible the owner confused person and people because of the usage of "first person, third person" which actually refers to the way a person speaks or writes about themselves or others.

For example, a story can be told in the first person (I was walking to the beach), or the third person (She was walking to the beach). You can also use second person, but generally only whe you are relating a story about someone back to them (You were walking to the beach).

Answer 2

You were in Quebec ...correct. They make up some of the rules as they go along. Plus translations from French are for them to decide, they figure,   not any others.