In many ways it's not preventing accidents that's important it's preventing people getting hurt.
Being a defensive driver can drastically change your odds of being killed by some random yahoo. Further, the kind of car you drive can make a significant difference and improvements in car design are largely responsible for a huge reduction in fatalities.
Remember, our dealing with V^2 and slow reaction time so a 50MPH car has half the energy of a 70MPH car.