Any industry that pays for its externalities is more expensive in production. My mother told me the river changed color based on what color the towns factory us

Any industry that pays for its externalities is more expensive in production. My mother told me the river changed color based on what color the towns factory used that day, when she was young. That did not change because people were guild tripped into not buying from them, or because someone found a way to be both more ecological and more profitable. The state changed the rules: your factory poisons the river, we close the factory and take your money. Economic profit does not favor ecology. No one would have invested into the R&D of wastewater processing unless the state threatens them with an economic equivalence of a death-sentence. Nowadays waste-water processing might be a boom market where profits can be made, but that is not some free market force that is independent from decades of lobbying.