I think you have to take into consideration what the country was like when the superhero comic books first appeared on the scene in the 1930’s. At that time, crime was mostly centered in the larger metropolitan areas, not the countryside. The mindset was also good versus evil, and things were more clear cut in people’s minds as to what they considered right and wrong. We’re talking the era of Al Capone here, and the comics were a symbol of the good guy winning and hope for the future.
Shortly after print comics appeared, the heroes became the stars of radio shows and crime fighting shows abounded with those and the detective genre.
You also have to remember that most people didn’t have their own transportation at that time, so criminals had to concentrate on the cities, where things were closer together. In small towns and the countryside, everyone knew everyone else, what their children were doing, and outsiders were easily recognized. When I was a kid, I lived in a relatively small town, a suburb of Los Angeles. We didn’t lock the door to the house unless we were going on a vacation, and we didn’t lock the car door unless we were parking in downtown Los Angeles. Now my car locks automatically when I put the key into the ignition and I never leave the door to the house unlocked.
I don’t think it was a cultural bias, I think that it was based on the way things were.