This analogy makes no sense. You can’t be serious.
In the case of most vehicle murderers, the vehicle was deliberately rented to the murderer, who then used it for a purpose for which it was not intended. The murder weapon being in possession of the murderer was not an act of negligence, it was a deliberate thing, a common act of commerce.
The correct analogy would not be your ridiculous one; it would be to, say, a person SELLING a rifle, entirely legally so, and the purchaser later using the rifle to murder someone.
No one is suggesting that. They are saying a person should be liable for their own negligent acts.
So as to read to personally defend himself and his family, a husband stores a loaded handgun in his nightstand sans trigger lock. While he is having a shower, his toddler pulls the gun out of the drawer and plays with it: “Look mommy! I’m a police off . . .” – BAM! She’s dead.
Here is a list of laws in various US states that could be applicable. By your statement above, you would not agree with the penalties of any of them when applied to my scenario. http://leg.wa.gov/Senate/Committees/LAW/Documents/SummaryOfStateChildAccessPreventionLaws.pdf
As far as the sidewalk massacre by the Ontario misogynist, it will be a wild ride as far as vicarious liability goes, for in Ontario there is a statute that holds the owner of a vehicle vicariously liable for damage caused by the operator’s negligence on a public highway, but (a) most (possibly all) of the killings were on the sidewalk, which in Ontario is not considered to be part of the highway, and (b) can cold blooded deliberate mass murder constitute negligence (for example, negligent in taking his meds etc.)? I wouldn’t begin to know whether or not the rental company will be held vicariously liable, but I somehow doubt it.