A marginal $20 has very little utility to rich people, but 15 minutes saved in traffic has large utility. Congestion pricing results in large utility gains to the rich.
A marginal $20 has tangible utility to poor people, and 15 minutes spent finding alternative transport also has tangible utility. Congestion pricing results in large utility losses to the poor.
KBB values are an imperfect proxy for individual monetary utility but could definitely be used to more fairly distribute the utility gains from congestion pricing.