If you want to learn about a society, you look at the people they revere as heroes; the men and women that they hold up on a pedestal.
For example, if you look at the old Greek myths, their heroes were bloody warriors with long lineages that stretched back and far. They were men of honor who bore their burdens with savage ferocity.
With Americans, you have to look to our comic books.
As silly as this might seem to someone who hasn’t been paying attention to the major box office draws of the last decade, comic books reflect who we, as a culture and a people, worship as heroes.
First, there is The Individual. It is always someone who has, by Fate or by choice, who has gone alone. They have shunned (Bruce Wayne) society or been shunned (Peter Parker). They must define themselves by themselves. They cannot allow society to dictate who they are. Even when it’s a team of heroes working together, they’re on the fringes of society (see: X-Men).
Second, The Vigilante; we like the hero who is apart from the Law. This builds off the earlier point: we like someone who doesn’t allow legal red tape to stand in their way. We want someone to stand up and strike a blow against what’s wrong in the world without having to wait for cops and judges and juries. We want speedy justice.
Almost never do we see the legal ramifications of a hero’s actions.
Thirdly, he cannot kill. At least, not willfully. There must be compassion. There must be mercy. The hero must be better than the rest of us. He will not let bloodlust or rage govern his actions. The hero stands apart from us in every, emotional, way. They must make the decisions we would not be capable of making, which is why we trust them in the role of the Vigilante.
Our heroes, the ones we revere in culture on television and movies and pulp fiction, are men and women emotionally unavailable, socially on the edge and disregard the law as beneath them.
In short, Americans revere sociopaths in flashy garb and gaudy dress.