When the private motorcar entered American cities in the early 1900s, its speed was incompatible with traditional street use. The resulting carnage led to a backlash against motorists and tight regulation of speed. The motoring industry and motor clubs recognized that they needed to redefine the use of the street in order for their vehicles to be useful in cities.
Through political wrangling and propaganda, our streets were reframed as corridors for throughput of cars. All other users were to stay out of the way. Safety was dissociated from speed and behavior, and the roads themselves were presumed dangerous for anyone other than motorists.