Okay just bear with me on this.

What if the reason none of the kids’ guardians had faces, except a few key details(bro’s shades, Dad’s pipe) is because the kids eventually forget what their parental figure’s faces looked like? They become blurry faded memories, and they only remember key things, the pipe, fedora, shades, scarf, that they wore? Their minds slowly faded their memory, so looking back they only see the key things on a figure, like a mannequin dressed in a storefront window?