The biggest issue in regards to battery shutoff switches or actuators of switches was to standardize the location on the vehicle to where first responders are instructed to go for the purpose of making sure the electricity is shut off.
The "why" of this requirement is also due to the fact that the rules, as presently written, allow for the use of an electrical shutoff to an electric fuel pump as being a positive fuel shutoff. There have apparently been occasions over the years where an engine in an overturned car was NOT running but fuel was being pumped out through the carburetor(s) due to the electric fuel pump remaining in operation. Wrecked cars often seem to have metal that gets bent towards ANYTHING that has the abilty to make sparks - especially if it is electrically live.
We actually played with lighting gasoline on fire with sparks from a single AA cell... and we easily ignited the gasoline (fumes, that is)... so... It has to have been some kind of problem id=f it got wwritten into the rules..... and again, most of us would like to know the reasoning behind or the explanation of the events that prompted the rule in the first place.... and.... the SCTA/BNI is, like most, if not all, sanctioning organizations, rather tight lipped about this sort of stuff....