Some things I don't understand...

I have been taught that when two parties fight, the blame is on both of them.

I have been taught to doublecheck, verify, question everything, search for more information, and not just believe everything I read on the internet.
People have agendas. People use propaganda. People lie. People deceive.
Some do it intentionally, some unknowing.
People share stories they have heard the way they understood them.
People share snippets of information and try to understand the world using these pieces as pieces of a puzzle.
People have theories and try to fit the data to support those theories.
People have beliefs, people have triggers, people have shadows, memories, baggage, filters.
People are wearing, if not pink glasses, then some kind of shades or glasses, that color everything they see, and make some things invisible and some things claring.
People make conclusions and then share these conclusions, and they might be correct and they might be not.
That sometimes the majority is right, and sometimes wrong. That the fact that "everyone says so", doesn't say anything about the veracity of the claim.

I have been taught that everyone is innocent until proven guilty; that it's better to let a crook walk than hang an innocent; that nothing is simple and self-evident - that we cannot know why people do things they do, because we are not those people, and we don't even know why WE do the things we do. That in order to be able to judge someone, one must walk in that person's boots. I have been taught that everything is connected. EVERYTHING is connected with everything else. We cannot just lift up one event in the history of mankind or individual human beings and use that to explain anything.

I have been taught that all the people are people, equal, react the same way, have the same principal values etc. That human brains are hardwired to work in a specific way, and they do, in every human being. I have been taught that this human quality is stronger than any cultural, ethnic, religious or other form of conditioning. That there might be individual differences, but as a group, humans are alike.
For example, most parents love their children, and children love their parents.
Life is precious.
One may not harm living beings that are weaker. A child's life is more precious than an adult's life.
People do what they think is the best for the group they belong in, and the size of the group starts with this planet and everything living on this, and then gets smaller and smaller, from humankind and nation to family and oneself.

Now, what I cannot understand is, how do people who agree on these theses to be true in most other events and circumstances, suddenly stop believing in this when the even and circumstances is Israel-Palestine conflict? So much so that they would rather stop talking to you all together than trying to understand how you see the situation.