The Opportunity Costs of Virtue?

From George Bernard Shaw's Preface to Mrs. Warren's Profession, found in Helen Reynolds' The Economics of Prostitution.

Prostitution is caused, not by female depravity and male licentiousness, but simply by underpaying, undervaluing, and overworking women so shamefully that the poorest of them are forced to resort to prostitution to keep body and soul together. Indeed, all attractive unpropertied women lose money by being infallibly virtuous or contracting marriages that are not more or less venal [mercenary]. If on the large scale we get what we call vice instead of what we call virtue it is simply because we are paying more for it. No normal woman would be a professional prostitute if she could better herself by being respectable, nor marry for money if she could afford to marry for love.

Last night, for "weekly movie night," which is the highlight of my kids' week, my 2-year-old daughter got to pick the movie, so we watched Cinderella - which by today's standards is kind of slow-paced, I thought. My wife and I both remarked that it takes forever for Cinderella to actually get to the ball, lose her slipper and then find true love afterwards. Most of the movie is spent on talking mice. Anyway, watching it, I thought about old feminist's critiques of movies like Cinderella which maybe set up a false view of feminity? But I wondered last night - maybe movies like this one caught such storm, and were so common, because by the mid-20th century, for the first time in all of human history, the typical woman began to have the opportunity to marry for love. I think Betsy Stevenson and Justin Wolfers have written about this somewhere. Anyway, stories about love had more real force - the dream of even common women marrying for love was not so far-fetched anymore.

So what of prostitution, then? There is undoubtedly something to Shaw's point. We have too much vice, if we do, because we pay more for it, but how and where are these incentives exactly? And is it a policy issue at all?