Cars killing people also usually do not have a wide reaching effect beyond the community it happened in.
I don't even know what you're referring to here. Sandy Hook I guess? That was 27. Other than that, there have been no mass shootings in schools with that many children killed since 1927.
I was using 2018 numbers - 23 is the total number of people killed in mass shootings in or near schools throughout the US that year. It hurts to say this, but I think the sober reality is that this is a very small problem, affecting very few people. On the other hand, every community in the country is impacted by automobile impacts killing children.