[NaOH]

For what you're describing, it's important to understand how the FDA and the laws are set up. As things are, package labeling is required for consumer packaged foods. The FDA inspects those facilities. That would seem like a good environment for your suggestion.

But there are other food businesses the FDA inspects that aren't subject to the labeling requirements. For example, this could be a local wholesaler, like a producer of pastries that supplies area coffee shops. That wholesaler will have maybe brought a daily box full of muffins to the coffee shop, whose staff then moved them to a display case.

Those situations have no labeling requirements, and no matter how much information is shared by the producer, nor how often, the café staff as a whole can't be trusted to get it all correct. I don't say they "can't be trusted" because that's an unwise procedure—and it is that—I say it because my business may as well be that local pastry producer.