Grading systems (at least in their contemporary form) are no more effective, because the grader can be very easily manipulated or show bias themselves. That and

Grading systems (at least in their contemporary form) are no more effective, because the grader can be very easily manipulated or show bias themselves. That and it's just a very flat method of measuring progress. It's systemic, ruthlessly bureaucratic and typically within the context of standardized testing. Social equalization was no doubt one of the motivations behind uniforms, though it's also likely a symbolic tool to foster groupthink and a superficial cloak of egalitarianism. There's many different ways to show your influence and being of a higher class than through mere clothing.