It may have been optimistic to presume that the frank imposition of fiscal measures, based on precisely monetisable social costs and the resulting tax adjustments that would bring social and private, market-based costs in line, could be routinely implemented in all circumstances. Yet, converging results from a number of broad-based and well-balanced studies have all implied that much stronger action than countries have been willing to contemplate - at the very least on air pollution and the reduction of climate change risks - is required to move towards economic optimality. The widespread lack of a meaningful carbon tax in many countries is a case in point. Stronger technical regulations, market creations, subsidies, improved transparency and reduced legal and institutional transaction costs, however, are all available as part of an arsenal of measures that can be used where the straightforward imposition of Pigouvian taxes remains elusive because of political obstacles resulting from distributional concerns. The well-being of their citizens and the welfare generated by their economies depend on it.