It really is more psychology than anything else. The bystander effect is a proven thing. There is also the fact that humans are just sheepish social animals who will harm themselves & others before they act disobedient or in an embarassing fashion.
Stanley Milgram ran some experiments on human obedience to authority figures and found that most people will torture someone either into unconsciousness or to death if asked to.
http://www.new-life.net/milgram.htm
http://en.wikipedia.org/wiki/Milgram_experiment#Results
They'd have an authority figure, a victim and a subject. The victim & authority figure were both actors. The authority figure told the subject to ask the victim questions and if he got them wrong to shock him with the shocks getting worse each time. After the voltage went to 150 volts the victim started saying he had a heart condition and wanted to quit. Then as the shocks went on the victim would pretend to scream in pain and yell for help and most people will still shock him until he passes out or pretends to die. Even after he passed out people would still shock him. Of course the shock device wasn't actually set up.
Sucks, but what can you do. That is how our brains are wired. People were sweating and terrified, some were shaking but most people prefer to torment and torture themselves and others before they disobey an authority figure. Even if the authority figure is impotent and wasn't an authority figure 5 minutes ago. Everyday people hate and are disgusted by themselves and attempt suicide, and most due it merely because something about their minds or bodies is disobedient to the status quo. People will destroy themselves and others before they disobey an authority figure or do something embarassing.
Milgram also found that if a second authority figure was present that said 'we should stop the experiment' (the first always said it should go on no matter what) that almost everyone would stop at 150 volts.
All in all, its really interesting. I'd recommend reading Milgram's book where he does alot of different techniques.
http://www.amazon.com/gp/product/006131983X/104-4535909-8949506?v=glance&n=283155
My point is that like it or not this is how our brains are wired. Even 'not taking a stand to stop the kidnapper' is a form of disobedience when you think about it. People just aren't going to do anything embarassing no matter what the benefit. Think about it, people attempt suicide and suffer depression everyday because they have done embarassing things. You can't expect people like that to take a stand socially. Its just the way we are wired. The best you can do is create societies and authority figures that say its ok to try to prevent these things.