I can give you an example that sticks with me of why some people don’t want to get involved.
A friend lost her older brother a few years ago, because he was a Good Samaritan, saw a man stomping his pregnant girlfriend, pulled the guy off of her (others were walking past, or worse, watching and recording with their phones).
The guy stabbed my friend’s brother, who later died in the hospital, leaving a wife and three daughters. The police caught the boyfriend, and during his trial, that same woman testified that the stranger had assaulted her for no reason, and her boyfriend was just protecting her !
Luckily, one of those people who’d been recording the incident showed what really happened and the guy went to prison—where the girlfriend, didn’t take advantage of the opportunity to relocate, but visited regularly, taking the child to see his father in prison. And the guy who tried to help her is visited by his family and friends in the cemetery.