It kills a lot of people. Whether the mechanism for it killing a lot of people is a large number of miles driven rather than a high rate of deaths per mile is neither here nor there.
It does not kill a large number of people in relative terms. In absolute terms, it kills an extremely tiny number of people; the death rate from traffic accidents in the US in 2018 was 0.01%.
It's one of the biggest killers of young people (e.g. looks like it's at least 25% of deaths of people aged 20-24?), so in terms of years of life lost it has a big impact.
