It's dangerous to take lessons from movies, which are, of course, not real. Back when 12 Monkeys came out, I was at a wedding reception and someone said that the movie demonstrated that even if one had a time machine, one wouldn't be able to change the past. My response was that it was a movie; it doesn't demonstrate any such thing. It's tempting for me to see a movie like, say, Traffic, and say "see, drug prohibition doesn't work"--but that would be a mistake. It's fiction.
Similarly, The Dark Knight says something about criminals and organized crime. I'm not sure exactly what it says, but it says something.
What I'd like to bring up is that poor Batman keeps having to fight these criminal organizations. (MINOR SPOILERS:) At the beginning of the movie, Batman, officer Jim Gordon, and the new District Attorney, Harvey Dent, have put serious pressure on the various gangs in Gotham. This somehow attracts a lunatic known as the Joker, who is interested in fighting Batman and sowing chaos, just for the fun of it. The movie seems to suggest that Batman can't win (or will at least have a hard time winning) because of the insanity and dedication of people like the Joker. The real question is, what about those regular, non-maniacal criminals? Why do they stick around? Why do they keep popping up? Why do they exist?
In the real world, the problem for police is not insane sociopaths who enjoy crime for its own sake. Well, mostly not, anyway. Why do actual criminal gangs exist? Why can't police stamp them out? The answer is simple: Organizations like the mafia make a profit providing illegal goods and services that people want. So long as people continue to want these goods and services--prostitution, drugs, gambling, and in the past, alcohol--these entrepreneurs will continue to enter the industry. Squeezing some of the businesses out of the market simply raises the profits of the remaining firms, just as forcing Southwest out of the airline market would make Delta and American and all the other airlines happy.
The mafia does sometimes participate in legal businesses, such as trash collection. They use their comparative advantage in violence to reduce competition in these industries, raising their profits. I'm guessing that they also use these industries to launder profits, but that's just speculation. They may use the fashion industry to launder money. Such legal rackets are surely small change compared to their trade in illegal goods and services. Of course, the people who are attracted to these markets are those who are good at, and comfortable with, violence. With a penchant for violence, an incentive to use violence to defend their (illegal) turf, and the funds to pay for weaponry, we should not be surprised when violence is the result.
Unless we're willing to give up the wars on drugs, prostitution, gambling, and other vices, we're doomed to keep fighting these battles over and over. Not even a super hero can prevent this. The problem isn't sadistic, homocidal clowns; it's the very real set of incentives created by the prohibitions we impose. One could make an argument that it is worth fighting this never-ending war in order to achieve some reduction of drug use or prostitution or gambling, but I would hope that the advocate of such a position would be honest enough to admit that those wars will be never-ending and violent.
Art Carden and I had an interesting conversation about Superman this morning. Hopefully he'll write up a blog entry sometime soon on the subject.