Running water

Utah is known for voluntarism and for love of family and for selflessness.
So why would people walk by a disaster scene and not help?
I found the question nagging at me after I watched the film "The Evanescence of Hope" at the 2015 LDS Film Festival, shot and produced by Loren M. Lambert.
Seems Mansour Ariazand had gone hiking on Father's Day a couple of years ago and tried to jump across a swollen mountain stream. He missed and couldn't get a grip on the slick, wet other side and was swept into the icy, cold water in Bells Canyon, down and over three different waterfalls.
Why he wasn't killed outright was a miraculous thing in itself.
Then when Jill Caree Anderson and Brynn Mudliar, and a couple nearby noticed him stuck between a rock and a tree branch, that was more than fortunate. Not only did Suzanne Jansen have training in CPR but Anderson and Mudliar were former flight attendants trained to stay calm in dangerous situations.
They were also willing to risk their own lives for a stranger.
They waded in and grabbed his head, holding his face above water so he could breathe. They ripped apart the clothing he wore that bound him to a big log poised to tip over and on down to the next waterfall. They stood and knelt and shivered in the icy water for more than two hours.
Ultimately they kept Ariazand alive until more help could come for him and them. Alone, they couldn't pull him from where he was wedged in the fiercely flowing water.
(First a rescue helicopter couldn't help with the equipment rescue personnel had on board. Secondly, another helicopter couldn't land where Ariazand was but had to find a spot further away which required personnel to hike back to help.)
It took time. It took patience and faith.
Meanwhile, those first on the scene were hollering for more people to come help them hold on.
Able-bodied hikers were all around and near them.
Some watched from a ways off.
One or two filmed the scene with their phones.
Some called 9-1-1.
On the film, Anderson asked what was wrong with people...why did no one else help? What was going on?
I've tried to figure this riddle out.
Did they think the situation was under control?
Did they think it was a training exercise?
Did people figure they would only make matters worse?
Would I wade into freezing cold water to try and help even though I'm old and can't swim?
I hope so.