By now, every mother in America has heard of Democrat Hilary Rosen’s recent charge that Ann Romney, the wife of presumptive GOP nominee Mitt Romney and mother of five grown sons, has “never worked a day in her life.”

Yes, the mommy wars are back.

Setting aside the question of whether raising children is “work” (it very much is, by the way), the mommy wars are so divisive because they’re framed in terms of values and choice. Where a woman chooses to work (at home or for a paycheck) is a proxy for her stance on career versus family and which she considers more “important.” Hence, First Lady Michelle Obama’s declaration this week that “families are off-limits” in politics.

But treating women’s work as an issue for culture and values misses the boat in a big way. Not only is it elitist, it denies the underlying economic realities of many women’s lives.

Maybe Ann Romney, as the wife of the “Buffett rule’s” juiciest potential target, has the luxury of a true choice between working at home and working for pay. For many women, however, the “choice” to work at home or at an office is not one that’s dictated by values but by brutal economics.

Many women can’t afford to stay at home, given the realities of today’s middle-class expectations. But many women also can’t afford to go to work, given the high costs of child care and other factors.

Nevertheless, by imbuing every mother’s circumstances with the gloss of “choice,” we end up ignoring the very real discussions we should be having about such issues as the lack of affordable quality child care, the continuing unwillingness of employers to provide flexibility at the workplace and the long-term economic impacts of taking a break from the workforce. These are the factors that make the “choice” between career and family so illusory for so many women.

In a remarkable survey of 3,781 mothers conducted in May 2010, the Working Mother Research Institute and Ernst and Young found that 55% of “career-oriented stay-at-home” moms would prefer to be working, while at the same time 71% of moms “equate work with something done only to pick up a paycheck.” In other words, many women who are in one arrangement would prefer to be in another.

On the one hand are the moms who can’t afford to stay at home. In March 2010, 65% of women with children under age 18 worked for pay, and women’s earnings are now an integral piece of many households’ finances.

Among married couples, according to the Bureau of Labor Statistics, working wives contributed 37.1% of overall family income in 2009. Moreover, 28.9% of these working wives earned more than their husbands.

Many Americans now take it for granted that a comfortable middle-class lifestyle can’t be had without two incomes. Faced with rising costs for college, gas and groceries, stagnant wages, and increasing lack of job and retirement security, two incomes are for many families a necessity.

But on the other hand are moms who can’t afford to work.

The Working Mother/Ernst & Young survey found that “the needs of my children” was the top reason career-oriented stay-at-home moms say they stopped working outside the home (44%).

However, the number two and three reasons were economic. Thirty-five percent of moms cited “the cost of child care” as a reason to stay home, and 26% said “the salary I earned did not justify the cost of working.” Further down the list of factors were “lack of flexibility” in work (12%), “lack of high-quality child care” (8%), and “lack of part-time work options” (8%).

While this survey focused on middle-class and professional women, the economic burden of working outside the home actually falls much harder on low-income women. According to the Census Bureau, families in poverty in 2010 who paid for child care spent as much as 40% of their monthly income on child care expenses.

Moreover, in a quirk of policy well-known to social policy wonks, women on welfare lose more and more of their benefits—including Medicaid and child care subsidies—the higher their earnings become. This “marginal tax” on benefits literally punishes poor women for their efforts to lift themselves out of poverty.

And while many companies are now embracing flextime, far fewer offer subsidies for child care, and even fewer offer innovative arrangements such as “job sharing” for women who want to work part-time.

For higher-income women, a final factor that could keep some women at home is the severe erosion of earning potential the longer a woman takes a break. Many researchers have found that workers who are “long-term unemployed” take a significant hit in their earnings when they eventually find a new job. Analysts at the Hamilton Project, for example, found a 17% average drop in earnings for people who lost their jobs during the Great Recession and were re-employed.

Conceptually, formerly salaried moms who now stay at home are similar to the long-term unemployed. But the reality is that they take an even bigger economic hit when they try to return to work, especially if they are professionals. According to Harvard economist Claudia Goldin, female MBA’s who took 18 months off to care for their kids earn 41% less than their male counterparts, while the “mommy penalty” for female lawyers is 29%, the gap for female MD’s is 16% and the lag for female Ph.D’s 33%.

It would not be surprising if some stay-at-home moms, facing the prospect of having their talents, education, skills and prior experience so undervalued, “decided” to stay at home for good.

The debate we’re having today is the wrong one. We shouldn’t be fighting over whether a woman’s choice to work for pay or to work at home is the “right” one. Rather, the real debate should be over whether there’s a choice at all.