Median HOUSEHOLD income in the US is $59,000. That's $29,500 for a single person working.
Family with two adults two children. Rent for a 2 bedroom is going to be in the $800-$1200 range most places, let's call it $1000 for easy math. You now have $17,500 to pay for food, clothing, diapers, utilities, transportation, medical expenses (kids go to the doctor a LOT), etc.
Let me know how livable that is.
- - - Updated - - -
We already do. Maternity leave is paid at least in part by state disability, which tax dollars fund.