Necessity is not the mother of subsidy

This is something one hears an awful lot:

So, if two incomes are mandatory for the basics of middle class life -- home, car, kids, dog, then childcare is now a necessity for most families. Those babies don't raise themselves. Yet, where is the child-care discussion in this presidential debate?

Food, shelter, or clothing are also necessities for children. But no one suggests that the government should provide them, except in the cases of those who are too poor to provide for themselves. Why should childcare be any different?