A family of two parents who work for $30,000, which seems like a pretty working-class salary, makes $60,000. A place with a MHI of $60,000 is usually considered pretty well-off. I wouldn't think of a family making $60,000 between two parents as super well-off.
Couple of things here. Men in work, on average, earn about $10,000 than women in work (figures from 2006; c.$32k and c.$22k respectively). That's the first thing to consider; it's very unlikely that both parents will be earning the same wage. Generally the husband earns a lot more (especially if the wife is, like a majority (still) of women in work, in part-time employment). Suddenly $60,000 starts to look more like $45,000 (say). And also you shouldn't forget that, even today, a lot of women with children don't work at all.
A single man making $60,000 is obviously a lot better off than two parents making $60,000. They have dependents; he doesn't.
