>huge externalities that have negative consequences for the world at large.

What are these negative consequences? The only ones I can think of are related to improper disposal (eg. littering), and would be present regardless of whether the material was recyclable or not. ie. if we replaced all the non-recyclable plastic bottles with 100% recyclable aluminum cans, the littering problem would still be there.

An idea is to get the companies to internalize these costs through a carbon tax which can be invested into climate change action (which is another story). At the moment, the consequence is that companies have zero incentive to act for the planet, so they will continue their behaviors.

Perhaps they pass some of these costs down to consumers which makes them less likely to purchase (and then litter) non-biodegradables. Or they can provide a cheaper good to avoid a carbon tax which encourages consumer to buy that alternative.

If the plastic is sequestered in a landfill, then what is the carbon externality?

Does decomposing plastic emit methane?

I think it's important to at least partially separate the issues of climate change from plastic pollution. For some reason these two have become entwined together in the public mind. We need to get a handle on plastic pollution, and yes, it's a product of the petrochemical industry so there is that, but it's not the same type or scale of problem as the emergency around tailpipe / smokestack CO2 or methane emissions.

I agree that just changing the material is not the solution. But it doesn't mean that the manufacturers get to skip their responsibility. In Finland we have to pay a considerable deposit by law (found in section 2: https://www.finlex.fi/en/laki/kaannokset/2013/en20130526.pdf) for every drink container you buy and you get the deposit back when you return them back to any store that has a returning machine (almost every single place you can buy those bottles). It seems that this is working very nicely, since the return rates are around 90% (https://www.palpa.fi/beverage-container-recycling/deposit-re...). Usually when drunk people are throwing beer cans to the streets, there's almost always someone picking up those cans for the deposit.

I'm not an expert, but I think the problem is that in the US, The industry would never allow that kind of decree to pass, since in this case "The manufacturers and importers of beverages fund return systems through different types of payments."

Forget recyclable aluminum cans, use refillable glass bottles with a meaningful deposit ($0.25 or more).

"They lied about the recycling potential to encourage widespread adoption of plastics."

?

Plastics are an absolutely incredible technology, to the point of revolutionary. They are used absolutely everywhere, in everything.

Nobody needed to be convinced of the utility of plastics, it's one of the most utilitarian things ever created.

So, they lied when they didn't even need to. Doesn't that make the lie that much worse?

They marketed their industry, just as every industry does.

They promoted something they understood to be a fiction because they knew it would offset reasonable concerns about their product. If you think that’s the core of marketing then we have very different ideas about what good marketing is.

Give this episode of planet money a listen: https://www.npr.org/2020/09/11/912150085/waste-land

It discusses extensively the knowledge the petro chemical lobby knew about the ability to recycle plastic and how little could really be recycled.