> I haven’t noticed any difference. SF still has tons of litter. Less of it is plastic bags ... Sounds like you have noticed a difference? Unless you are sugg

> I haven’t noticed any difference. SF still has tons of litter. Less of it is plastic bags ... Sounds like you have noticed a difference? Unless you are suggesting that there is some "conservation of litter" principle that ensure that the total amount of litter is fixed, so reducing one kind of litter causes other kinds to increase? As for your needles argument, would a tax on needles really reduce the total externalities? Sure, it would result in less needles being bought, but that may result in move people sharing needles and transmitting diseases resulting in a much more significant cost. Something should be done about the needles, but it is not clear (a) that taxing them is a good idea, and (b) what this has to do with plastic bags.