In 1974 the Equal Credit Opportunity act (ECOA) was signed into law, and while there are many good points to this legislation, it also created a legacy of unintended consequences. For instance, on the good side it eliminated taking into account your race, religion, national origin, sex, marital status or whether or not you get public assistance in regards to your application for credit. In addition, the lender could not speculate as to what your plans were in regards to having or raising children, and thereby for dual-income couples had to accept each person's salary as a true reflection of the earnings of that couple, without availing themselves of the option of discounting a woman's salary or speculating that at some point, one or both of them, might be out of work, for some period of time.
This meant, in practicality, that the housing lender would now take a snapshot of your current combined salary, and from there, would be able to offer a suitable mortgage package and loan for a house. Not too surprisingly, as this is America, the more money that you made, the more house that you could afford, so that in 1974 as noted by census.gov the average price of a home in America was $38,900, whereas in 2010 it was $272,900, and if we were to re-price the home taking into account the devaluation of the dollar, the average price in 2010 should have been $172,056, while the actual difference between those prices is $100,000, which represents a real increase in 2010 dollars of 58.6%, which is substantial.
In fairness to the builders that sell homes, modern-day homes do have more amenities than homes of 1974, to which, though, the most telling difference between homes of today as compared to 1974, is as noted by aei.org that: "Over the last 40 years, the average home has increased in size by more than 1,000 square feet," which would certainly account for a lot of the reason why housing pricing has increased so much over the last forty years. The strange thing is that the overall family size has decreased from about 3 per household back in 1974, to just over 2.5 people per household today, so that the increase in home sizing has little to do with families getting larger, because they haven't.
All of the above, would imply strongly, that the purveyors of housing, saw the fact that since dual income wages were no longer being discounted by the mortgage lenders, that this meant, for a certainty, that they now could sell homes that were bigger, better, and more expensive, since more verifiable income having been approved equated to more house that could be bought. After all, the home builders have a vested interest in selling bigger homes that retail for more money because these homes are more profitable that your traditional smaller starter homes, often, substantially so.
You know that it is a sad state of affairs, that mathematics are not a particular strong suit of a significant amount of Americans, and therefore thirty years to pay off a loan, allows a lender to take a relatively large number, and break it down into something that looks manageable, and probably is manageable, if you make certain positive assumptions about employment and salary, and don't take into account that most families have family responsibilities and obligations that cost both money as well as time, as well as health issues, and that unanticipated events do happen.
The thing about dual incomes is that if you are already earning at full capacity that means that you do not have any room for error or safety margin, should things not work out as desired. The purchasing of a house is for virtually everyone, the biggest voluntary debt that they will take on in their entire life, to which, the better part of valor, is to be more practical and budget savvy.