But if a man earns enough to pay for the needs of his wife in addition to his own, that means he is paid much more than her. I wouldn't deduce that from the man's total compensation, since it essentially is an expense like any other.
Childcare / alimony is not an expense like any other because in many legislations you cannot really decided to stop paying that expense, see
e.g. [1]. In the US you typically go to prison pretty swiftly if you refuse to pay.
