[Earw0rm]

If people had to pay the true cost of their decisions up-front, we'd make a lot of different decisions.

That said, I got quite into this stuff a few years back, and determining "true" cost can be harder than it sounds. Externalities, positive or negative, have to be measured against a baseline, and deciding on where that sits is subject to opinion and bias.

[teiferer]

You don't need to get it perfect though. The right incentives get you most of the way. Perfect is the enemy of good.