I going to guess that referring to inmates by numbers would be widely criticized as inhumane by many human rights groups. It would be an uphill battle to keep something like that going.
Inmates are commonly referred to by their number in prison -- as far as the prison system is concerned, they're not 'Leland Highsmith,' they're A319445 -- it's tied to their phone calls, commissary purchases, meal records, medicine records, and health records.
