The real problem, I think, is when fairness conflicts with effectiveness. If the idea is to do the best by each individual then I guess you’ll want to select the punishment which works best at improving the behaviour of that individual (if you can).
You might want to select the method of behavior modification to get the best result with each individual, but psychology psycho analysis and sociology show , at least if you look beyond the straight jacket of Doc’s Anglo Saxon empiricism , that punishment of any sort isn’t actually very effective at achieving transformation .
Oh sure it serves other social functions , deterrent , suppression, reinforcing social divisions and structures, maintaining false dichotomies of sex, gender , race……and suppressing recognition ( ie of Patriarchal structures and processes ) ..but then even the language we use divides, separates and isolates us as the powerless individual within a hegemonic idealogical matrix………which we commonly call societal values .
Thats a clear message from post modernist theory . , and you see it acted out in society every single day …..