It's probably a psychological trick to get kids to believe Santa exists and then pull the rug out from under them as they get older, to disprove Santa, which suddenly invalidates his existence when in fact it's quite possible the opposite is true.
Few dare to delve into the fact that given Santa's superhuman powers, he is indeed likely not of this earth . This was even explored in a documentary that detailed this over fifty years ago.
Simple food for thought this holiday season, God bless Santa.