Death penalty proponents make a big deal of this contrast. They claim that European societies are just as barbaric as American societies—although they don't actually put it in those words.
Are you interested to know how some American websites interpret this result? If so, read on, but before clicking on the "Read more" link I want to warn all Europeans that you may not like what you read. If you have high blood pressure you'd better skip it.
Here's an explanation written by Wesley Lowe on the Pro Death Penalty Webpage. Remember, he's trying to explain why European governments have abolished the death penalty in spite of the fact that a majority of Europeans support it.
Differences between European parliamentary government and the American separation-of-powers system also play a role. Parliamentary government may provide voters with more ideological variety, but it is much more resistant to political newcomers and fresh ideals which may support different political views. In parliamentary systems, people tend to vote for parties, not individuals; and party committees choose which candidates stand for election. As a result, parties are less influenced by the will of the people. In countries like Britain and France, so long as elite opinion remains sufficiently united (which, in the case of the death penalty, it has), public support cannot translate into legislative action. Since American candidates are largely independent and self-selected, they serve as a much more direct conduit between public opinion and actual political action.This is so astonishingly ignorant that it leaves me speechless. Let's hear from other Americans on this point. Do you really believe that the government of the USA is more democratic and more open to fresh ideas than governments in Europe? Do you really believe that the US Congress is more responsive to public opinion than governments that have a parliamentary system? (While replying, keep in mind the frequency with which incumbent American politicians are turfed out of office. Contrast this with parliamentary systems where it's not uncommon for 50% of the seats to change hands in a general election.)
Basically, then, Europe doesn't have the death penalty because its political systems are less democratic, or at least more insulated from public opinion, than the U.S. government.