Because where you gonna walk to? Your gonna walk 5 miles to Target and back?

That'd why sidewalks is polish. Most sidewalks I see outside of tight downtowns are useless and barely used, and they aren't free to build and they don't generate anything if no one uses them...

I've been to and through Chattanooga a bunch of times. It is a city where you almost definitely need a car for basic subsistence.

The poor areas are super poor and semi-distant from goods and services. Biking somewhere from the poor areas, unless you have time and energy to spare, is going to be a big undertaking most of the time, not even accounting for the hills.

They are not a default thing anywhere in America that developed after WW2. Most car centric places dispense with them as an "unnecessary" cost or, where they do exist, they're disconnected decoration with limited utility.