Treating everyone the same blindly is the very essence of fair. It is, however, unjust by your sense of justice. There's a vast difference between the concepts.
You're also assuming a specific sense of justice - you're assuming that the utility of money is linear. (That is, giving up $10 is the same to someone earning minimum wage and to someone earning $150k).
You can hold that view - but recognize that it is a specific view, not an essential definition of fairness.
You can hold that view - but recognize that it is a specific view, not an essential definition of fairness.