We have many laws and regulation in place to lower children MV deaths. This includes things like seat belt, booster seat, child seat expiration and couple zones, and rollover protection.
The fact of the matter is that
“The previous analysis, which examined data through 2016, showed that firearm-related injuries were second only to motor vehicle crashes (both traffic-related and nontraffic-related) as the leading cause of death among children and adolescents, defined as persons 1 to 19 years of age. Since 2016, that gap has narrowed, and in 2020, firearm-related injuries became the leading cause of death in that age group. From 2019 to 2020, the relative increase in the rate of firearm-related deaths of all types (suicide, homicide, unintentional, and undetermined) among children and adolescents was 29.5% — more than twice as high as the relative increase in the general population.”
So outlawing vehicles is not proposed but laws, and regulation to control risk appears to be effective.
https://www.nejm.org/doi/full/10.1056/NEJMc2201761