Every "bet" consideration needs to include possible loss, not only the odds. Losing your child is for many people not that far off from losing their own life, so people tend to react in a very cautious way.
Usually losing a kid is due untreatable diseases and bad parenting (like driving them to school without taking proper safety measures and suffer the consequences of an accident)
There's no evidence that going to school alone is more dangerous than staying home with grandpa's guns