I don't see why caring about plastic bags is mutual exclusive from caring about automobile free cities. I'm 40 and have never owned a car. I'm a big NotJustBikes and StrongTowns proponent. We can for sure debate car dependence and what policies we should advocate for. But this was an article about biodegradable plastics.
Montreal is shutting down a ton of streets every summer to make them walkable, and we've built out an extensive bike infrastructure. All great things! We could make public transportation free.
I don't understand why you insist that we need to solve the "real" problems of pollution before we dare think about other smaller, easier to solve problems. It's not like we're playing a video game where society only has a finite amount of elbow grease to apply to this set of issues. We can reduce plastic bag pollution while also working toward reducing the pollution from automobiles, tire wear, and whatever else you on your own high horse have deigned to be "real problems".
These are not conflicting goals.
"We" are not working on solving those other actual sources of pollution. We're just making people's lives worse. People think they've "done their part" by not using bags, when they haven't done shit.