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.
It's even (often) in company's selfish interest to have regulation so that they aren't forced into a race to the bottom.
this is why I'm always very astonished when European regulation is frowned upon by reflex
Yes and: "regulations" is just a scary words for "rules".
Yes and: Policy proceeds rule making. Rules try to encode incentives and disincentives to achieve those policies. For better or worse.
Yes and: Surplus, and therefore overuse of, unhealthy foodstuffs (eg HFCS) is the result of pro Big Ag policies. Which are often in opposition to public health interests. So we (taxpayers) are paying to create lifestyle diseases at the same time we're paying to mitigate those same diseases.
I know you know all this. I hate to go meta on the UPF debate; but there really is an easily identified root cause.
The very first priority to mitigating lifestyle diseases should be:
Stop making it worse.
/rant