"The market" only cares about things that are factored in to prices. External costs like the environment are currently not factored in so the market will never

"The market" only cares about things that are factored in to prices. External costs like the environment are currently not factored in so the market will never optimize for them. If you simply set a carbon tax, overnight the whole market puts a huge effort in to lowering their environmental damage because now that damage has a number next to it and can be optimized for.