Then the automobile industry began the process of normalizing traffic fatalities.
Core to their approach was an emphasis on human error. Accidents weren't due to systemic decisions (or corporate greed). It was all "human error". Pedestrians who didn't yield to cars were "jaywalkers" causing accidents.
The industry lobbied against restrictions like "speed governors" that would keep cars from going too fast and funded education campaigns to teach a new generation that roads were for cars.