There's much more to the changes than the women's movement. We are a very consumer-oriented culture, and there are a lot more consumer items that are considered necessities - those, in turn, necessitate dual incomes.
And then there's the media.....
Think of all the things we pay for now that our parents didn't pay for...
phone until 1990---one, no cell phones.
tv until early 80's free, no cable, no satellite.
Cost to own a home computer till early 90's...huh, what's a home computer?
Internet access before 1995, a net to go "inter" accessing what?
car for each of your two kids? Ever heard of a bicycle?
2nd car (try, one car).
Wii? Is that french? XBox who?
Central air was the floor fan in the middle of the living room (hence, "central").
Cost to run a home with a dishwasher (that was me), working dryer (that was the clothes line outside, atleast in the summer).
HOA fees? He better not be paying for no HOA!!
School fund raisers?? No, the school operated just fine without having to buy all that wrapping paper you won't use.
Stop me if you've heard enough...
...and we wonder why momma ain't never home to bring those kids up right.