Why do so many people have automatonophobia (fear of ventriloquists' dummies, wax figures, automatons, etc)?

I had to look up this phobia to find the name for it. I've had this fear myself since childhood, and I know I'm not alone. I think it's also related to the fear of things like clowns, Santa Claus, Easter Bunny and mascot-type costumes, all of which used to creep me out. Some still do. But why are these things scary?