That's because he's not really real and doesn't like kids anyway.
He's actually an out-of-work security guard who only took the temporary job because he has gambling debts and is behind with his alimony.
I've heard that he'd prefer to spend the build up to Christmas sitting on his sofa wearing only his vest and shorts, watching horse-racing on TV whilst swigging cheap beer out of cans.
All that "Ho Ho Ho Merry Christmas!" is just a load of flim-flam.