My "Santa" was not a saint man but an old man who was responsible for the cold weather in the winter, and he didn't come on Christmas eve but on New Year's eve. I never wrote letters to him, and was surprised to hear on tv one day that he actually lived somewhere, with a real address. He didn't have a wife, but a young daughter. I always thought of him as make-believe, because he always brought what I asked from my parents.
As a child, I always had a clear distinction between make-believe and reality, so I never thought my parents were lying when they were playing along. But they didn't play with me much, I recall mostly solitary play time. Santa and others were not brought up in my discussions and games with peers, too. Hah, I never played as if there were fairies in my games. A tooth fairy is something I find ridiculous.
But one could argue that such was the Soviet upbringing which avoided superstition as much as possible.
I have a big problem with this. You're making the mistake of expecting children to be like adults and seeing childhood as something that people should just get over as soon as possible. Did you really hate your own childhood make-believe days that much?
Moreover, when you say to your child that fairies, etc, are not real, he goes to other children and spreads the word, interfering with other parents' intentions. I dislike this a lot.
Although I agree that fairy tales and Christmas should not be about consumerism.