[donw]

Addendum: I'm seeing a common theme in the responses.

When there's a coordination problem, but the equilibria state is unsustainable (such as overfishing) or lower-value (imagine competing electric grids with different voltages and frequencies), then government regulation can be useful by either imposing unilateral costs, and/or by defining a common standard.

There is the issue of avoiding regulatory capture, but I suppose that's for another time. :)