>Arguably, paper bags are "better" because they don't require petroleum to produce
Is using petroleum intrinsically bad? There are externalities with oil extraction, but growing a monoculture of trees for paper isn't stellar for the environment either. Also, plastic is stronger than paper (on a mass basis), hence plastic bags can be thinner than paper bags, which also carry advantages. I feel people irrationally like paper bags because it's more "natural" than plastic. It's insufficient to judge whether plastic or paper is better for the environment just by coming up a list of bullet points. A total lifecycle cost analysis is needed. Of the literature I've seen, paper bags are not better for the environment overall than plastic.
>Failing all of the above, it is unlikely used paper bags end up on barges destined for the developing world for recycling, only to be dumped into the ocean.
addressed here: https://news.ycombinator.com/item?id=23763885