But people mother because it's a biological instinct. Money is an artifical construct that has nothing to do with it.
Society can place an arbitrary value on caring, but to what end?
If you went round the world and asked people whether they'd be expected to look after their parents in their old age, on the whole they would say 'yes' (with varying results from country to country), but if you then asked them if they thought the state should pay them, the answer would nearly always be 'no'. Whereas if you asked those same people if they think somebody should be paid for mending their TV or whatever, they'd all say 'yes'. Your family doesn't pay you for looking after them. And neither does the state.
Caring is something people do out of a sense of duty, not for reward. Should their be a reward? Well no, because people see it as their duty to do so. I don't get paid for looking after my children and I wouldn't expect to be.
Obviously it's possible for society to get to the state where people no longer see such a duty, and in that case financial incentives make sense for society, but not to a commercial level.