My mom would get very aggravated about margarine. I vaguely remember her kneading coloring into the white brick, so it must have been at the end of WWII, when butter was in short supply and presumably my parents broke down and bought margarine as the cheaper, available spread (might have been rationed). Despite living on a dairy farm, we didn't make our own butter. A ban on selling margarine colored to look like butter was just one of the measures dairy farmers took across the country to limit its inroads on their market, and not just in the U.S., but in Europe and Canada as well.
Identity is big in food. France and the EU fight hard to preserve the cachet of champagne, which can only be produced in Champagne. Such fights over cheeses and other foods are old hat. More recent are fights over things like "soy milk" and "almond milk". And the controversy over "organic" including hydroponic vegetables. And the latest controversy is "clean meat", which is meat produced in the lab/factory from cell cultures.