It isn't about punishment or indignation since neither can prevent that kind of practice from happening indefinately afterwards. In some places this kind of practice has become their tradition with all sectors of the society involved. You can't punish everyone.
As well, I bet, many locals probably consider defending this practice defending a natual right, a legacy. I recall a line from some 電視連續劇 years back. It was so long ago that I can't neither recall the story nor the title of it, yet this line impressed me ever since given its brutal irony. It was monologized by some leader of some nomadic people that carried out periodic invasions southward in order to harvest the necessities from agricultural peoples for their own survival. Upon hearing that the south had eventually organized an army to resist their invasions, the leader thought it was unfair: "The grass feeds the goats, and the goats feed the wolves. This is the law of heaven. We are the wolves. Now, the goats are resisting the wolves. This isn't right!"
Regarding our case here, what the central government should do is, I say, sending a replacement working term of qualified individuals to completely take over the local goverment for a sufficiently long period of time since the local government is already thoroughly corrupted. I believe, this was Italy (?) once did when the Mafia integration with some local government was hopelessly complex, thus irreversible.
When a place isn't yet thoroughly corrupted, it is like a basket of good and bad apples. One can remove the bad ones and keep the good ones intact. When a place is thoroghly corrupted, it is more like a swimming pool. There is no peeing section in a swimming pool as to be removed. One can only replace the whole body of waterr.
This is the right moment to implement the powerful central government. If it doesn't do anything in cases like this, why should a powerful central government be necessary?
A powerful central government and a weak one (無為而治) respectively have their advantages and disadvantages. The former should be expected with a taller moral call and more righteous involvements in undoing injustices done to the powerless. This is a justification of the powerful central government itself for a weak one shouldn't be able to do that.
