Just vs Fair
In "Doctrinal Discussion" Dr. Gayle Woods writes:

To be good parents, a couple cannot treat their children the same. In other words, they will not be fair. Children have different temperaments, strengths, needs, weaknesses, and are different ages, so they cannot be allowed the same freedoms and privileges at a given time. It is the same in spiritual matters. God in His infinite wisdom is not fair. He knows our frame. He is aware of our level of spiritual maturity. He knows our strengths and weaknesses. He remembers how we have been hurt in the past and how it affects our thinking in the present. He knows our history of dealing with trials in life. He knows us. He treats us like individuals. He doesn’t look at a manual to find the universal answer for our problems. He gives us what fits us at the time. He is not fair, and that is a blessing! He always does what is right because He is not fair. He is just.

Source: Biblical Family Values, Adult Teacher's Insights, page 68.