You aren't interested in Justice, you're interested in equality, but ONLY in the issue of taxation.
If you were really concerned with justice, then you'd ALSO be concerned about the injustice of enormous income disparity.
Are you?
I think not.
What is inherently unjust about economic desparity? That somehow implies unfairness. That in turn implies that one is not in control of their earning capability, which is by in large not true.