Why do you think it was important for the Aztec to be able to tell commoners and nobles apart just by looking at them?

It was important for the Aztec to differentiate between commoners and nobles because social distinctions played a significant role in Aztec society. Nobles held positions of power and privilege, while commoners had different responsibilities and rights. Being able to discern one's social status at a glance helped maintain order and hierarchy in Aztec society.