"Superman has no values of his own, so he's content to just uphold the values of the ruling class; this prevents him from becoming a dangerous vigilante a la Frank Castle, but it also means he has no legitimate opinions of his own where crime is concerned. In Paul Dini's storybook series on DC superheroes, Batman had to deal with gangland violence, Wonder Woman fights terrorism, and Superman tries to end world hunger. This is no accident – Superman is way too morally simplistic to deal with complex things like the "wars" on drugs or terror. In Batman: War on Crime, Bats comes up against a young boy holding a gun on him. Batman, understanding the complexity of crime and the reasons for its existence, talks the kid into dropping the gun and giving up a life of violence.
Superman would probably just use his heat-vision to melt the gun, then put the kid in prison where he'd become a hard-bitten thug who'd murder somebody a few months after getting out.