It is a commentary more on the sad and unfortunate increase in "single mother households" than anything else. The study isn't not saying that "for 40% of MARRIED COUPLES, the primary earners are women". If the study was confined to households where both a man and a woman were "wage earners", it would probably be more like "5% of women are primary earners".How can the woman be the primary earner in 40% of families if they are earning less than the man?
But the study was designed to produce absolute bullcrap because of the flawed and inaccurate nature of its methodology. The study is a terrible study to use for the reasons it is being used & quoted in the media. No - the study just took a look at the total universe of all wage-earners and made no distinctions for single parent homes, women who voluntarily withdrew from the work force, women who CHOOSE not to participate in careers at all, or women who choose not to engage in dangerous (but higher paying) jobs. It was a stupid study designed by people with an agenda to produce ONE bullet point line that could be repeated by idiots on network news programs, blogs, Jezebel, feminist magazines, and other misinformation outlets.