How is there more coupling between a company's profit and negative social externalities resulting from its actions when the company is privately-owned? If anything, I would think there's rather less coupling in privately owned companies, as a public company is at least forced to be somewhat transparent, publish SEC releases, subject itself to audits, etc. For example, unlike a private company, it wouldn't be possible for Google to engage in a material transformation of their business without accounting for it publicly towards their shareholders.