If you are speaking about me personally, I do not have a tooth fairy and I did teach my children about sex in a way that young ones understand. They don't have an Easter Bunny either but they do know about a resurrected Jesus on the day of Resurrection.
God or Santa?
God or Jesus?
God or the tooth fairy?
God or the Easter Bunny?
Many to you these are small thing that aren't important but to some who love Jesus with their whole hearts, an idol is an idol, not matter how accepted culturally.
Well, apparently, God has a different message for me than He has for you when I've prayed about this issue.
My faith allows the two to co-exist. In the end, the reality wins out, the fantasy doesn't.
I have no problem with you discussing this with me in this fashion. Nor is problem with you in our differences in faith, it is in your deciding not just to refuse to perpetuate the myth, but in actively undermining my responsibility as a parent and dispelling the myth.