Based on the 2010 US census, more than 80% of the US population lives in urban areas. That was up a bit from the 2000 census. I live in the 'burbs, and rideshare is practical here. It will be more practical when it doesn’t rely on a human driver.
I expect that in the not-too-distant future you will be able to hail a car that is equipped with car seats. That’s a pretty common preference.