The Toothfairy vs. Zeus

Recently, I've been wondering: how many traditions and superstitions of the past were like Santa or the Toothfairy or the Easter Bunny. — all of these are carried on by people who do not believe in them, and yet who, year after year, do the correct things to keep up the mythos.

How many of the myths and folktales of the past were like that…people knew they weren't there but did the things anyway. Did anyone ever put out milk for brownies who thought brownies would come clean their houses? Or did everyone know it was like cookies for Santa?


(In the Roanoke roleplaying game, John's character the cowboy sorcerer kid immediately filled the brownie's milk bowl with whiskey. His room got painted puce and chartreuse.).)