The point of congestion pricing is to let market mechanisms determine where the optimum is.

Well, the market decides where the optimum is *in response to* the price set by the government. So the government can decide at least approximately where they want things to end up by setting a higher or lower price.

	▲	bgirard 3 days ago \| parent [-]
		Right. It finds an economic optimum limited to what people are willing to pay and their perceived value from that. That optimum doesn't naturally weight more complex factors like for the trade-off for the smog generated from your travel.