Not being the person in the situation it is easy to say "I would do this ...". I know that I have found myself in a few situations and surprised myself in how I handled things because I ended up handling them differently than I would have expected until being in the situation.
I think that most of the time people don't get involved, even when things seem odd. Watch that show "what would you do?" and you'll see that even in extreme situations this is often the case.
BBM
My reactions (non-reactions) are just one of many reasons why I'd hate to be in the place of one of the family or friends. I've been told that I'm an odd mixture of cold and sensitive.
People are always saying that I'm one of the warmest and friendliest people they know, but I've also been told many times that I'm one of the least emotional or excitable people they know.
Some examples: when I was 12, I woke up at about 6:00am to find a drunk man I'd never seen before sitting on my bed. I was confused, but I sat and talked to him for over 1/2 hour before I stood up and ran from my room to my mother's to get her (not because I was scared, but because I had no idea where the house he was supposedly looking for was.) The guy was gone before we got back to my room, but my mother was freaking out. We eventually found out later that day that he was the ex-husband of the woman upstairs. He had threatened to kill her and was just released from prison (for assault and attempted murder of his mother), and had robbed the gun and sporting goods store the night before stealing a couple guns and a bunch of ammo. We lived in a duplex, and my bed happened to be right in front of the door that led to an interior stairway to the upstairs unit.
I was raped 3 times as a teen. At 14 by a friend's older brother, at 16 by my boyfriend's twin brother and at 18 by a "nice guy" we met at a wedding dance/reception and my mother insisted that I accept a ride home from...she thought it was time I spent time with some respectable people for a change! I never screamed or cried during any of them, and never reported any (my family had me pretty well convinced that if anything like that ever happened it would be because I had asked for it, and nobody'd believe me anyway...even with all the bruises the 3rd time)
I have been to more funerals in my life than most people have been to parties. All 4 grandparents, both parents, most of my aunts and uncles, and well over 100 people I considered to be friends at one time. A lot were from cancer or other 'natural' causes, a lot were from car accidents, but one was murdered by her ex-husband, 3 were shot by friends/acquaintences, 1 was shot by a family member, 3 committed suicide, 3 were murdered by unknown people, and a variety of others. I have never shed a tear at one of the funerals I've been to, and almost never at home - definitely not in public.
I have no doubt that I'd be worried sick if it were one of my kids or any other kid I'm close to, but I think I'd be lynched here and probably in the media if I were ever questioned about the disappearance of one. Even my son asked me one time (he was about 10), "Mom, why is it that the more something bothers you, the more jokes you make about it?" I've also had friends walk up to me and ask if me if the person I was talking to was going to be needing a blood towel. When the person asked what they meant, they'd say, "From that smile on her face, I'd say she's going to deck you any minute."
Too late to make a long story short, but anyway - not only is it hard to know what you'd do in a given situation, but it's also hard to know what someone else has gone through to account for their actions in that same situation.