The reason the American people are so against gun control is because they view a gun as a usable tool and that shooting someone is a perfectly reasonable solution to a problem. I have little more than anecdotal evidence but there was an incident where a man deliberately drove into the back of another car out of anger (this is in the US). The majority of comments on the story said that the person who got hit ought to have got out his gun and shot the offending driver.
Here in the UK, few people would consider shooting someone, possibly fatally, as the best and first option to almost any scenario.
EDIT: The justification that those advocating shooting the guy gave was that the act of deliberately crashing into a another car is the use of a deadly weapon which could have killed someone. Therefore it is acceptable to retaliate with a firearm.