How shall I put this? Plastic supermarket bags, while terrible in many ways, are particularly good at the removal of a particular form of non-toxic canine waste that often afflicts our urban and suburban areas. Indeed, they might be the perfect vehicle for this sort of job. One major complaint about plastic bags is that they are disposable, but for this particular sort of job, disposability is a requirement of the task. (And anyone who is a dog owner I think will agree with me that paper bags just don’t do the trick as well).
Yes, yes; people can purchase plastic bags specifically marketed as useful for this task. But that is just the sort of thing that is inconvenient enough for lots of people simply to avoid. Put another way, if municipalities ban the plastic bag, there might be another sort of street pollution that goes up.
And no: I’m not volunteering to be the Principal Investigator on such a project.