I thought she put it well enough to understand, but here's another stab at it:
Fifty years ago, if the husband gets a job offer in a town of 10,000 people with one main employer, he'll take it and relocate the family there. It doesn't matter that there's no career prospects for the wife, because she isn't likely to be working in a career job.
Today, the husband (or wife) gets the same job offer, but the family doesn't take it because the other spouse works in public relations (or whatever) and there are no good jobs of that type in the small 1-industry town.
Fifty years ago, if the husband gets a job offer in a town of 10,000 people with one main employer, he'll take it and relocate the family there. It doesn't matter that there's no career prospects for the wife, because she isn't likely to be working in a career job.
Today, the husband (or wife) gets the same job offer, but the family doesn't take it because the other spouse works in public relations (or whatever) and there are no good jobs of that type in the small 1-industry town.