Yes, this causes problems.
> and then if you make it a standard there needs to be testing for compliance
Why would there need to be any additional testing? If anything I'd expect "may" foods to need less testing than an accident-prone "no" food.
https://www.fox9.com/news/new-us-food-label-law-unintended-e...
> Some companies include statements on labels that say a food "may contain" a certain product or that the food is "produced in a facility" that also uses certain allergens. However, such statements are voluntary, not required, according to the FDA, and they do not absolve the company of requirements to prevent cross-contamination.
> Instead, some companies have taken a different approach. Officials at Olive Garden said that starting this week, the chain is adding "a minimal amount of sesame flour" to the company’s famous breadsticks "due to the potential for cross-contamination at the bakery."
> Many companies now routinely attach Prop 65 warning labels to any product of theirs that they think might possibly contain one of the 900 listed chemicals without testing to see whether the chemical is really present in their product and without reformulating their product, because it is cheaper to do so than to run the risk of being sued by Prop 65 enforcers.