This game theory problem, where consumers are buying unhealthier options because they're cheaper, and companies are producing unhealthier options because they're more profitable, is exactly what regulation is for. I don't understand why we've all collectively forgotten why regulation exists and become so cynical that it can actually work! Actually I do understand: it's industry interests spending hundreds of billions of dollars on intentional misinformation and government capture for a half century.

A reasonable counter-argument is "but the science is extremely muddy here, so effective regulation is especially difficult", which is unfortunately true, but I'd point out that the science is extremely muddy largely because of industry efforts to intentionally poison our understanding of nutrition.