I didn't see daycare there, but guess it might be under the top category. That would probably be most of it (we spend over $15k on it). If not how do they spend $20k on food+gas..?
Some people in the reddit thread pointed out that "Private Preschool" probably means daycare. That expense would make more sense then, since childcare ain't cheap. I'm not sure though, that's just one guess.