Paper bags don't generally decompose in landfills (it doesn't decompose anaerobically).
We have very different ideas about what's important to the future of the planet. Heck, I care about people, the planet is only important by inference.
All laws are enforced by men with guns, or they're meaningless. Do what makes you happy, but if you should want to impose your will on others, you're talking about force (or the threat thereof).