It’s the inherent reason the ruling class wants people dumb, poor, and preoccupied. If you’re of reasonable intelligence, have free time, and the means to address concerns as they arise you are more likely to be able to educate yourself about injustices that are extremely infuriating to the point of reaching either nihilism or anger

Does the person working 2 jobs and raising 3 kids have time to read the news in depth? To read books on theory and philosophy? To read about the history of atrocities and research a conflict? No. But the upper class child of a lawyer who went to school for free and got to take a gap year when they felt stressed? They just might, if they can look past the consumerist glitter that’s constantly distracting them.

Kohlberg theorized that morality develops with life experience and there is a stage called post-conventional morality that not everyone reaches. This is where we start to move beyond maintaining social order by following externally designated rule systems (like laws) and start to define internal ethics that doesn’t inherently align with those laws. Laws themselves become social contracts rather than rules and must be changed when they no longer serve the greater good. At the highest level ones personal ethics supersede laws and it can even become necessary to break laws that are unjust intentionally

This is illustrated by responses to the Heinz dilemma, which is what the initial research was based on https://en.wikipedia.org/wiki/Heinz_dilemma

Reaching post-conventional morality requires stronger abstract reasoning skills. That requires education and (to some degree) genetics. As a result only a small portion of the populace make it past stage 4 (which again, is follow the rules and obey authority to keep social order). If you give people more education and free time to develop their empathic morality outside of external moral systems (eg religion, laws) more people would get there, probably. I think it’s already happened, most of the research on how many people fall into which category is 20-40 years old at this point and a lot has changed significantly in that time. But again, a system that allows for this is a system in which people start complaining loudly and demanding change to injustices so we’ve also seen tremendous destruction to worker compensation, the education system, etc in that same timeframe so who knows