Price is just a symptom or manifestation. People naturally see it as unfair to take advantage of someone based on a power imbalance or information asymmetry. So charging an excessive price or paying a starvation wage is just one way to take advantage, but there are other non-monetary ways as well. Attempts to impose "fair" price or wage controls by legislative fiat or cultural norms are doomed to fail because they don't resolve the underlying cause.