Yeah, that guy got unnecessarily personal. Let me try.
You're right that civil judgements (and, though you haven't mentioned it yet, reputational brand damage through public exposure) are important checks on harm, but they break down in particular circumstances. In the first place, they're not a fair fight: corporations are able to limit, or even prevent, access to the court system by forced arbitration, jurisdiction changes, or intentionally running up attorney fees beyond what any plaintiffs can afford to risk. They also have ($£€¥, again) larger megaphones than any individual can reliably command.
The toy example of glass in a soup can makes for a perfect case, but civil suits are impossible to pursue where harms are long-term, diffuse, cumulative, or simply too difficult for a jury of lay-people to understand. For instance, we all know that lead is harmful, but when multiple sources of lead exist it's impossible to prove (to the standard correctly required by the courts) that this company's lead caused your particular illness. It's similarly impossible to prove that any particular cancer-causing agent caused any particular cancer, even when we know statistically that it has raised the cancer risk profile of millions of people, and therefore been a causative factor in many deaths.
If we insist that the only mechanism for redress be individual companies held to account in individual cases, we either give up on the idea that corporate behavior can be aligned with the public interest, or (worse?) we make sure that politically-disfavored companies will be scapegoated by the media or the courts, while better-connected players get away with anything at all.
Please allow me to forestall one possible counter-argument: if you, as my Libertarian-ish relatives do, reject outright the idea of "public interest", then we won't have much to say to each other: our world-views are simply too different. Otherwise, I'm interested in what you have to say.