“I am pointing out that this is an accepted practice for crime and punishment in the Game of Thrones universe.”
Except it really isn’t. Imprisonment sure, but beatings and starvation? Nope. That’s practiced by outlaws like the Bloody Mummers and Ramsay Snow, not by legitimate authorities.
Even imprisonment is only normally done pending a trial, which happens swiftly in this universe. The Sparrow, on the other hand, imprisons people and tortures them until they confess, and only then do they get a trial. Of course, since a confession has been coerced, the results of the trial are a foregone conclusions, so his trials are kangaroo courts.
Hhmm, immediate executions by Ned Stark and John Snow.
Others who received summary execution with no trial: Beric Dunderion hung by Lanisters, and Mance Rayder burned at the stake by Stannis. Doesn’t seem that trials are a priority for the elites.
The trials conducted by the elites had preordained outcomes for people who were not guilty of the crimes they were accused of.
The people who were to be tried by the Sparrow were guilty of the crimes they were charged with.