One answer is optimism bias. This means that, compared to others, we tend to be more optimistic about our chances to succeed or survive in some adventure. This is one reason why people smoke in spite of risk of lung cancer. Individual smokers accept that others will die of lung cancer, but they don’t think they will.
I believe this bias is transferred to movie characters when we are drawn in to feel invested or enmeshed in what happens to a film’s main character. For example, in one of the Bourne films with Matt Damon, he survives a car chase in a tiny car in Moscow. I drove a Ford Festiva (tiny car, 40 mpg). Any one event in that chase would have ended the car Matt Damon was in, but I wanted to believe he and the car would survive, so I accepted what happened.
A problem I come across in scripts is when people insist their stories be realistic. I once tried to help a writer with a main character who was sickly and weak from a traumatic event. The author refused to have his main character be more active and heroic at the beginning of the story because it wouldn’t be realistic. It wasn’t interesting, either. His main character was too weak to drive the action of the story.
A movie viewer wants a main character to be larger than life so they can experience a larger than life adventure through them.
If you’re writing a screenplay or novel, it’s your job to create a main character who will take a viewer or reader to places they want to go. Keep in mind that in life, many people feel stuck. A larger than life story character who refuses to be bound can be a real pleasure to journey with.
To read some of my longer reviews of popular movies, visit my website or check out my writing workbook, A Story is a Promise, available on Amazon Kindle. Or, find me on Google+ and tell me what you think.