A recent piece on Shanxi coal miners in Time by Simon Elegant and Zhang Jiachang hits the nail on the head with this remark on Wen Jiabao's efforts against mine deaths:
"In a country famously assumed to be authoritarian, like China, you might think such repeated investment of personal authority by a top leader would produce rapid results."
Pei Minxin's explanation for this seeming paradox makes the most sense: authority is so dispersed and the central government is so hesitant to grab that authority back (other than in tightly military-guarded places like Tibet and Xinjiang) because there is rent seeking behavior up and down the chain of command that MUST BE SATISFIED.
Without corrupt local officials on its side, the government not only loses any presence at the village and township level, but it is faced with a potential new enemy, as Kevin O'Brien and others have shown. Local officials can bolt and go populist.
The potential for this is shown most strangely and tragically in the cases of mine bosses and small town despots who are able to rally workers to STOP the shutting down of unsafe mines.