> The problem is that the people not paying for these externalities don't want to, have no incentive to, and are not required to. They lobby to avoid laws and regulations that would make them do it.

Perhaps the externalities are exaggerated then? If you say something is scarce and the market says it's abundant, who's right? You? Why?

The fact is that Lego isn't, to any meaningful degree, contributing to adverse outcomes by using petroleum as a feedstock. The market tells them they got the right answer. Their oil use is a drop in the bucket. They shouldn't feel pressured to worsen their product over moral and aesthetic pressure from activists.

> The economic argument doesn't work, so it's a little hard not to frame it as a moral issue instead.

The market is working just fine. The trouble is that the moralizers don't like the priority stack rank the market produces and seek to use various forms of non-market power to get the outcomes they want. People doing this makes us all worse off. Trust the market.