Yes, many families lived on one salary back then; however, they lived on less, bought less, and did not have as much accumulated wealth as they do now. Lots of families COULD live on one salary today...they just are unwilling to do so.
Since you say that taxes were NOT lower in the 50's, please clarify the tax structure for me. Because I had always read that they were lower in the 50's, but I'm willing to be educated about it.