You’re off by about 20 years - it was the 1920s when car manufacturers were able to get legislation restricting public streets to their customers[1] - but also this ignores the magnitude: yes, cars have always been a public health hazard but the manufacturers reversed a multi-decade safety improvement trend a decade or two back because it boosted their profits, and that happened only in the United States. If our roads were as safe as Germany’s, while still not absolutely safe there would be an annual death toll reduction in the tens of thousands and 1-2 orders of magnitude more for series injuries. That’s huge even if it’s not perfect.
One person dying does not equate to "unsafe roads" in the way that "widespread adoption of motor vehicles" does. People were frequently trampled by horse-drawn carriages prior to cars, but not at anywhere close to the rate after cars became so ubiquitous.
First, yes, but it’s not like people weren’t killed by horses or trolleys either. The death toll was never zero but it went up sharply when everyone was expected to drive much heavier vehicles at higher speeds.
1. https://www.vox.com/2015/1/15/7551873/jaywalking-history