I grew up in a small town where there were no sidewalks unless you counted 4 sides from 3 blocks downtown. As children, we didn't pay much attention to the rule that required us to walk on the left facing oncoming traffic but we did make sure that we were on the edge or even off of the pavement when a vehicle drove by. Most neighbourhood streets were our playgrounds and we shared with other road users as the need arose. That system worked well for us and I can't recall anyone being hurt aside from one girl who had been clipped by the mirror of a passing pickup truck.
This system probably worked well for us because people parked in their driveways rather than on the streets. There was always room on the sides to be seen and walk safely. The village council did not see a need to build sidewalks so when roads were paved or rebuilt none were constructed. Some municipalities followed suit, at least in the quieter areas.
Fast forward 40 years.