Let me reiterate. Violence is not the answer for one reason and one reason only. Once it starts and everyone joins, it will be very, very hard to stop.
edit: be
The gunman made his own gun, in a country with ultra-strict gun laws. The Unabomber made his own bombs. The Seattle mall Islamist knife attacker refused to stay down after being shot multiple times.
My takeaway: political terrorists are particularly motivated. Secondly, gun laws slow them down but don't stop them.
I don't believe this is the same thing.
One is an adversarial problem where a living thinking being is evil and trying to attack you.
In traffic, most people are just trying to get somewhere, and then accidents happen.
Do you think traffic lights help if someone goes out with the explicit intent to kill others via their car?