Same with Zwarte Piet, although the suggestion that he is going to carry the naughty children off to his home in Spain is a bit of a clue, don't you think.

Zwarte Piet is usually explained either as a Moorish 'servant' (slave, essentially, one would presume) or blackened by soot from climbing through chimneys to enter houses. The longstanding practice of having him speak in broken/child like language and made up perceived mock 'black' or (later) surinam accents is a bit of a give away when it comes to racial/racist roots.