Mainly by making motorists responsible for killing pedestrians. Instead, in America you mostly don't even get fined for running over a pedestrian, as "it's just an unfortunate accident", even when you have chosen to purchase a vehicle that makes it harder to safely navigate around pedestrians.

Consider: Do other countries even have the concept of "Jaywalking", which was explicitly an attempt by vehicle manufacturers to blame pedestrian deaths on pedestrians.

I'm not talking about all streets in a given city obviously. Specifically in Japan, narrow streets with no sidewalks are omnipresent in neighborhoods, and they're still far more walkable than a typical US neighborhood street with sidewalks.

Check out Tokyo. Most streets have no sidewalks. Very walkable.