This makes me think consumer protection agencies should have more UX researchers involved in thinking about how best to safeguard the average customer from thes

This makes me think consumer protection agencies should have more UX researchers involved in thinking about how best to safeguard the average customer from these non-software dark patterns. Lots of different mandates or regulations might help - but which is the most effective and least heavy-handed? E.g. one could require a standardized way to display per-ounce prices next to the absolute total price, or simply require the per-ounce price is listed equally as prominently as the absolute price, or require notices to be posted on the packaging for 6 months after changing its size (apparently Brazil does this), or require said notices on the shelf next to the price, etc. Perhaps user researchers could also build up data to make the case that regulation is justified, e.g. demonstrating that the majority of consumers are unaware that the effective price has changed.