It's worse than that. Even in the households with vehicles, there will be members who are unable to use them due to age or disability. So at the very least they will be dependent on another family member for basic getting-around-town capabilities. Together with households that are too poor to afford a vehicle, about 31% of the US population doesn't have access to a car. (Note that is inclusive of non-driving children -- but IMHO they should be able to use the city, too.)
This is why public transport and good urban design are so frigging important. Imagine if some other demographic of this size were forced to be dependent on others for going shopping, going to the doctor's, etc. It would be an outrage, because, in truth, it is a outrage.
This is why public transport and good urban design are so frigging important. Imagine if some other demographic of this size were forced to be dependent on others for going shopping, going to the doctor's, etc. It would be an outrage, because, in truth, it is a outrage.