[giantg2]

I really don't see a benefit to creating conflicting/competing policy. You have people who would rather keep their lawn than go to concrete based on the tax being more than the subsidy (assuming one time subsidy vs yearly tax). The policies undermine each other. You can't just slap a single policy over a multitude of others and think that's more beneficial, right? You have to look at it from a systems thinking perspective, which would require evaluating the interactions and n-order effects between that one police and all the others. If you're doing that work already (clearly politicians don't, based on the existing poor policies) then you might as well fix the underlying issues since it will allow the policies to function more effectively.

"but expect to pay for the negative externalities of that."

But what do you think that money will actually do? Is it going to prevent issues? I don't think so. It won't even cover the costs of actual damages in many cases.