Why do parents lie to their kids?
Seriously this is never discussed. Parents decide to make up fictional stories of a magic man delivering parents instead of reminding their kids about the true spiritual nature of our universe - not referring to any specific religion though you have to agree there is more to our universe than 'we came from nothing when something exploded from nothing and made something' logic.
Remind your kids of the real spiritual realm instead of the Santa tale which they grow out of anyway so what's the point?