Insurance by the Mile?

I've read about plans similar to PAYD, which is described in this article from Grist's "Soapbox" column, and find the concept really intriguing. Seems like the more we can price resources on a per unit basis, the better chance we have of conserving those resources. Counting on personal virtue alone just isn't getting us there, and even makes those who do participate in conservation efforts resentful. Certainly that's not the emotional response we're soliciting...