Actually, it's mostly Gummint greed.
Look at ANY chart describing the percentage of individual income stolen by Gummints (USA) from 1945-present and you will find out WHY mothers "have to work."
When I was a young'un, (the fifties, smartass) the combined Gummint bloodsucking was only around 15% of my father's income.
Now it's more like 40%, and some say it's 50%.
So THAT'S where the disposable income went--and don't try to tell me that "investing in Gummint" is productive investment, with the exception being defense...