A spontaneous order can neither be just or unjust.
This is because A spontaneous order has no personal intention and No personal intention in a spontaneous order means no justice or injustice.
Nature is an Spontaneous order. Therefore, Nature can neither be just or unjust.
Nature can only be just or unjust if it is a personal creator, who has the ability to intend.
The economy is part of nature or it is, at least, a spontaneous order. And that is why, like Nature, The economy can neither be just nor unjust.
References
Hayek, F.A. (1978). L_aw, Legislation and Liberty, Vol. 2: The Mirage of Social Justice_, pp. 31-32. Quoted in: Thomas Sowell. The Quest for Cosmic Justice.