The traditional mother's role is compensated. They have their expenses, like heating, electricity, shelter and groceries, paid for by the breadwinner.

They are of course not compensated for what they provide their children, but the same applies to the breadwinner, whose expenditures on the children are not compensated. That's what child-rearing is: an expense in money and/or time.

This is not exclusive to the "capitalist system", and it does not just apply to the traditional mother's role.