Really? You never heard, "why buy a cow if you can get the milk free?" Women have known that rule for centuries and, until recently, their life depended on what kind of man they could get. 80-100 years ago, it wasn't like today, when a single woman could get a job/career, house, etc. and it wasn't the rule to marry for love back then. A woman used the bargaining power she had and competition that was practically giving away a major part of it was not appreciated. Our current attitudes about family are still based, in part, on ideals from before 1900, when wives traded sex and housekeeping for food and shelter and children were necessary as homemade farm hands.