Which was added while making it, and not by anyone related to the restaurant itself. It’s a failure of the ice cream distributor and the FDA who clearly allowed this ice cream maker to improperly store personal food items and food items to be distributed in the same place. What reasonable expectation would a restauranteur have to check the product they receive for drug contamination, especially since they do not expect the food to have any sort of drugs in it to begin with and they choose distributors based on the information and grading the government gives the distributor? I would expect them to check and make sure the food isn’t out-of-date or spoiled, not for them to test it for drugs. If it didn’t look, smell or taste different enough for people to think the ice cream was “off” in any way, there is 0 way for the ice cream shop to expect this sort of situation happening.