I think it's a lot more consistent than first glance would suggest. Here's the principle I've seen acted out numerous times:
1. I want something
2. Because I want something, someone owes it to me.
3. I have not attained what I want.
4. Therefore, someone is being unfair.
5. As a result, I am angry, and I will act out my anger until someone is punished, or I am rewarded.
Everything else is just intellectual clutter, and emotional white-noise. The behavior is actually quite infantile, with one exception: infants do not yet know how to rationalize their unmet needs into false obligations on others.
The fundamental (but false) principle that my unmet need constitutes an absolute obligation on someone to provide it to me, is essentially an echo from an infancy deprived of basic nurturing. Everyone you see in those parks once needed, but never got, a parent ready to devote himself entirely to his child's well-being - and later, pushed his guilt for that failure into his child, who then internalized the unmet need and projected the desire to resolve it onto the world.
As such, as long as we continue to treat children as chattel, we will continue to exist in a world of politics and war.