Every employee should be treated the same. Most people just want a level playing field that offers the same opportunities to all. Common courtesy and respect also go a long way to bolster morale of the company.
Some companies such as Honda Manufacturing do this objectifying as mentioned in the previous post by assigning points to certain company infractions. However, despite the rubrics, etc. human nature is such that certain personalities do not respond positively to others; this is a fact of life to which everyone must adjust.
A common response to situations like these is to create a rubric, a code of conduct or a statement of policy.
Objectifying the values of the workplace allows for a manager to deal with behavior as a focus as opposed to dealing with personalities (a much messier prospect). This is simliar to the teacher's and parent's mantra: Punish the behavior, not the child.
I don't see much difference between managers being fair to their employees and teachers being fair to individual students. There are always personality clashes between people, but both teachers and managers owe it to themselves, their companies/schools, and their employees/students to treat people humanely and equitably; otherwise, it reflects badly upon the character of both the person and the business (or school), and poor employee/student performance and morale often follows.
I don't think that there's any formula for doing this. All a manager can do is to try to be fair. They have to be aware of the different personalities of their employees and their different needs. They need to be aware of their own personality and how it meshes (or doesn't mesh) with that of each employee. This kind of awareness will make the manager more able to be fair, but there's no magic way to just automatically be fair in all cases.