[boringg]

Externalities are actually starting to get baked in (depending on jurisdiction) or are essentially getting mandated in by policy (i.e. no coal in-state via political process). For most of North America coal isn't financially viable unless it gets political beneficial treatment - its been losing to natural gas for awhile now.

To be fair to your comment though air pollution relating to climate warming has been treated as a tragedy of the commons problem for ever.