Yeah, I suppose you’re right. But I feel it is much more “merciful”, in my opinion, if one were to not hold the threat of the authorities against someone. It brings to mind St. Joseph, when he heard of Mary’s pregnancy, planning to divorce her quietly and not have her face the authorities and public disgrace. Or when St. Padre Pio stopped a man from almost murdering his wife and still did not make him go to the authorities (which would have been attempted murder). If priests were to do that, then people wouldn’t be as honest in confession and there would be much more sinfulness and, even worse, people ending up in Hell, which in my opinion, is much worse than someone forgoing jail time.
These are just my thoughts, I might be wrong and you can disagree.