Because sometimes addressing inequality requires addressing situations unequally. As a (hopefully) completely uncontroversial example: if you were a governor or

Because sometimes addressing inequality requires addressing situations unequally. As a (hopefully) completely uncontroversial example: if you were a governor or president during Civil Rights era desegregation, evaluating whether to deploy National Guard soldiers to enforce desegregation of schools, it would be absurd to apply that equally to schools which are segregated and schools which are integrated.