You can aim a gun.

The comparison does follow that a purely offensive object is being used as a form of safety blanket (No one can rob my house/kill me in an accident! I've got a SUV/handgun!) but the fact is that while a perfectly safe gun is a useless scrap of metal, a (theoretical) perfectly safe car is not. So, what it comes down to is a highly dangerous weapon that performs its function versus a highly dangerous vehicle that fails to perform.