It's not just a battery charger in your house, it's every single electrical component in the house that could burn it down. I've been to house fires where the cause was an appliance on the kitchen counter, lightning, improperly disposed of ashes, woodstoves, main panels, electrical outlets, fireplaces, or sometimes they just can't pinpoint it. In my eyes there's no point trying to cover all the potential issues because there's always something that could start a fire, and that's why we have insurance. If my houses catches fire, i'd prefer it burns to the ground so the insurance company cant nickel and dime me to death, which happens all the time.