4 ideas
Commander Hu is sent with troops to suppress reported bandits in Yanzhou, Zhejiang, and finds almost none. His soldiers plunder and burn the villages they were sent to protect, and Hu reports the operation to his superiors as a great victory over a bandit uprising. He and his staff collect promotions and rewards, so an imaginary threat becomes a career asset and ordinary villagers bear the cost.
When posts can be bought through official contribution schemes, the holder treats the office as capital that must pay back its purchase price plus profit. Extortion of subordinates and the public is not a lapse but the business model. Each buyer then sells favors and appointments downward, which spreads the debt through every level of the bureaucracy.
Instead of handing over cash, supplicants buy goods such as antiques or curios at wildly inflated prices from a shop tied to the official they need. The markup is the bribe, and the paperwork shows an ordinary purchase. The same object can be sold back and resold repeatedly, so a legitimate-looking trade becomes a toll gate for access.
The novel has no central protagonist. This structure shows that the rot lies in the incentives and the reporting chain, not in individual character. Replacing one bad official only brings in another who responds to the same pressures.