Caring for elderly parents in the "Me Too" era. I am not dealing with this, but I know someone who is.

Segoline, I think Tothill has some good explanations.  Even today, I've seen a "let's just bury the whole thing" response or the claim that the little girl is responsible because she "aroused" the man.  Remember there was a stereotype of male sexuality that pardoned aggression.   You know "real boys will be boys".  Over the years I've dealt with men who really don't get it that harassing, grabbing, etc. IS abuse.  Not just a guy doing what a guy does.
I'm thinking of Penn State and Jerry Sandusky.  Of course his family knew, protected him, and the result was all those boys abused. 
Then you get to emotional abuse - I've seen people who are undoubtedly being abused emotionally and they don't even understand what is happening.  They think this treatment is normal and that they are somehow at fault for their suffering.  How many men have you run into that believe in male dominance? The idea that a woman's task in life is to be submissive? To always facilitate whatever a man wants?
You've probably had the Bible quoted to you - but keep in mind that this is cherry picking AND talks about marriage. Read the WHOLE text carefully.  People not married to each other don't have to submit at all - they stand perfectly equal.
I can see that in a filial responsibility legal context there is a problem because asking an abused kid "why didn't you report your parents?" is simply not in line with reality.

I'm confused:
Are yo talking about elderly people BEING abused or the abuse THEY perhaps instigated years ago?

As a "survivor" of YEARS of serious abuse by a brother---this kind of talk really triggers me.

What is the actual question??

So, I'm confused. Unless you live in a filial responsibility state, adult children have no legal responsibility to provide care or support for their indigent parents. Even in those FR states, I haven't heard of states enforcing them, except in the case of fraud on the part of the adult children.

Are you saying that State Medicaid programs are refusing to provide long term care to folks?

Based on family experience and talks with friends, most abuse, of any sort, was hidden or buried by families. Never to be discussed in the family let alone public. So up until 20/30 years ago it was not reported to the police.

One friend tells a story about the creepy uncle who was never left along with the little girls in the family.

When I reported an attempt on my life by a former partner, the police would not do anything, that was 32 years ago. It was witnessed by two other people and one of them, the brother of the man and was able to get him off of me, he saved my life. My father took the side of the man who assaulted me. So even if abuse was reported, there was a great deal of victim blaming. My father later paid for a lawyer for that man to sue me for custody of our child, even though he was and still is an addict and alcoholic. So, my Dad is lucky my brother is willing to house him, because I would not.

I also have a story of a boy who was sexually abused by his step mother, it went on for years until he developed body hair. He never said a thing. She turned to his much younger brother and that boy immediately told his Dad. That happened in the 1960/70's and the woman was never charged, the parents just got divorced.

So I would not expect there to be any 'evidence' that would meet a judicial burden of proof, but that does not mean terrible things did not happen. Or that parents were not either aware and did nothing, or were the abusers themselves.