And to actually prepare for a sneak attack from a moving vehicle, you would need to have your gun trained on each car passing by, just in case it has a terrorist in it.
Nope. One, the car would have to slow down, if the terr'ists want to hit anything. Two, they'd stick the gun out of the window so as not to go deaf. Three, shooting from a car is difficult even under the best of conditions. Four, nothing says you (the armed citizen) will be the primary/first target, in which case returning fire will be much easier.
It's not a fool proof method of preventing X percentage of terror attacks. It's a method of not being scared, of being willing to fight back. Of governments not hindering those of their citizens who are willing and able to defend themselves and those around them. There is no way, aside from a massive Big Brother state which would limit all freedoms, to prevent all the attacks. And a ridiculously small amount of people dying to terrorism annually is not cause enough to sell away your freedom. So that's an important distinction to make it. It's not so much that having armed citizens will prevent the majority of attacks, it's a mindset thing. "Attack us if you will, but we'll fight back, we won't be afraid, and we won't be easy targets."
Terrorism feeds off of the panicky sheep fear. It's useless against a society that is not afraid.
