It feels like you are looking for an argument that I am not making.
> I have certainly been the only human on public transportation at times.
Their are always a driver of a vehicle, or other passengers coming in less than an hour or so...
> Moving entirely to public transportation would eliminate that precise risk while introducing others
I never imply to move entirely to public transportation. The best solution is multi-modal transportation.
> Keep in mind how rare children dying in cars is today.
This is an argument I despise, specially related to cars... Any death is bad, and should be avoided, whatever how!
A simple example, in the USA, is the whole wave of rules, laws, etc. after the attach of 9/11.
Less than 3000 died[1] because of it. That's equal to only one month of road death in 2020 or 2021[2].
[1] https://www.cdc.gov/mmwr/preview/mmwrhtml/mm51SPa6.htm
[2] https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/...