Sure they might do that, just as a for profit company might. The decision by either would face the same trade off - an increase in costs that their customers/p

Sure they might do that, just as a for profit company might. The decision by either would face the same trade off - an increase in costs that their customers/patrons may not care about or be willing to pay for. The answer for both is the same - price externalities so that the decision to pollute less is economic rather than moral.