If you could answer this question, you wouldn’t have to write a story.
There is NO ANSWER to the question “What is the inequity all four Throughlines are looking at”.
The whole point of an inequity is that it is something that can’t be described - it can only be approximated, or guessed at, by the four different perspectives.
Only when you have an account of all four are you able to assess the appropriateness or inappropriateness of the actions or decisions taken to resolve the inequity.
But you still will never be able to define it.