Not really. Lots of societies have required accused criminals to be tortured until they confess. Presumably they would generally only torture people they believed were guilty, but there was no reason to be more confident the person was guilty after confession than before. The confession was purely of ritual significance.
Gladiatorial combat was used to help preserve the social order. Public executions were often just that but skipping the combat part, and people would often cheer them on like a football game.
You'd be surprised how little people care about innocence and justice. They care more about the entertainment value and reddit drama of discussing the convictions than actual justice or truth.
People want to hear that bad things are being done to "bad people", and won't interrogate that label too deeply.
