The theory behind treating spouses as if they each earned half of the couple's combined income is that marriage is presumed to indicate economic unity between two people.
Also, provisions exist to treat spouses separately as persons.
Advice for women on how to treat spouses.
G.E. is a family organization tending to treat spouses and employees as a part of a team.
A colleague who spent much of her time treating abused spouses once told me that battered women had to leave their husbands five times before they stopped being drawn back.