At a political level, a Pigouvian tax also introduces significant shifts in the allocation of environmental use rights, which can translate into real economic losses or gains for different groups of users or producers worth billions of dollars. This often explains the ferocious resistance to environmental taxes, for instance carbon taxes, by those who would need to pay them. On a conceptual level, it is the information problem that constitutes the true Achilles heel of the Pigouvian approach centring on the optimal pricing of externalities.