Why do some people turn and look away when someone is being hared/ually hared/molested and abused?

I have seen people who try to make victims feel like they misunderstood what happened, exaggerating,need to calm down, that they can't report an abusive and controlling parent etc. Yes there are people who do help the victims but why doesn't everyone help? Victims who abusers delude themselves to think they didn't hit them etc.. when they did.. Victims whose abusers think they're above the law so opening up the victim's mail,confiing bank card and holding onto thier money. forcing them to stay home while they go out, making them quite their jobs or telling them who to go out with and who to go with, being verbally abusive as well as physically. I don't understand why people see the abused etc person but don't do more or anything to help.