Why doesn't the working class, the bigger of the two classes, not simply eat the rich? There are reasons, tons of them. Mostly, the fact that the rich spend a lot of effort to prevent it, understandably.
The justice system isn't just, it never is. In fact I struggle to find any historical example of the justice system that would be good, it is at most good enough. But society still chugging along, enduring the unjust system, along with other unjust systems. Until it doesn't, which lead to the new society with the new, maybe slightly better system, which ultimately is as shit as the previous one.
That's kind of the corner stone of the human suffering, you know.