Costco forced to recall food that was not labeled to the requirements. In this case, the butter is supposed to be labelled as containing milk. Now, you and me, we know that butter is made from milk or cream, but only a great fool would assume everyone knows what they know.
And, these labels aren't just for the lactose intolerant consumer. The allergen information is fed to computers that handle the automated distribution of products to various uses. That butter might end up as one of a hundred ingredients in a prepackaged donut. If the allergen isn't on the label, the person doing data entry may not realize it. Disney World killed a doctor just last year because of allergen exposure, and that shit happens all the time. It only made the news because Disney tried to enforce an arbitration clause the husband digitally accepted when he tried out Disney+.
The point is, this is not a story about overregulation or snowflakes being too sensitive. Costco fucked up, and their fuckup puts lives at risk. If you happened to buy the improperly labelled butter, congrats on your good fortune, because Costco is going to pay you for their fuckup. You don't have to discard perfectly good butter unless you cannot have dairy, and you didn't yet know that butter contains milk.