Robert Nozick found some good arguments why the NAP doesn't work in theory. The best is that it doesn't allow for degrees of aggression. Shooting a gun into a crowd violates the NAP. If you put one round in a chamber and spin the drum of a revolver and then play Russian Roulette with the crowd, the NAP is violated just as much though the chances of the gun firing are 1 / 6. You can universalize that and say no matter how many chambers are in the gun, the NAP is violated when you point it at a crowd and pull the trigger. That's when you have hit the jackpot, because from a certain chambersize on (say 400 000 chambers in an imaginary gun), driving a car is more lethal than shooting the gun. Thus, driving a car violates the NAP.