Justice is as said in the quoted post equal oportunities for everyone not equal outcome(rewards).
Look at it this way is it justice if you work 8 hours a day and get 20$ and then I come and do exactly the same work for 30 mins and also get 20$?
Ofc it is not justice.
If everyone gets same rewards than people will stop giving effort and than those who can make the world better wont care about it and wont give effort in making it better because their reward will be the same as for the guy who drinks beer all day ad farts.