Yah its misguided, I do a fair number of park/etc cleanups. The old school ultra thin bags break down really fast in the environment when exposed to UV. Most of the time, when I tried to pick one up they simply disintegrated into powder. Plastic drink bottles OTOH, those things are everywhere and seem to last forever.

Just over the past few years the heavier reusable (mostly plastic) bags are starting to show up everywhere now, and they don't seem to break down as fast. I have yet to see any of them in any state of decomposition.