It's pretty insidious. Kids getting shot at school is rare, so it's reported on. Kids getting killed by drivers is so common that bereaved parents have to beg and plead and scream at their elected officials to get them to even notice, much less do anything.
Recency bias and a tendency to miscalculate the odds of something that is A) awful and B) played on repeat for days. Also, angry reactionaries always demand that the authorities “do something about this!”
Those factors pretty much guarantee that there will be a swift, uncalculated, often showy response to public tragedy.
Essentially. I distinctly remember an article about some multi-car pileup a couple days after a mass shooting, and noting that the otherwise unremarkable car accident ended up in 2x the causalities
It appears to be feared disproportionately.