I do understand. I have been in the position where I could have put something into the food I prepared and served, but the consequences would have been harm to a customer, no matter how repulsive I thought that person was, and the destruction of my business.
As for the thought process of the customer making someone do what they do not want to do, sure, they may briefly think “she might poison me”, but the next thought will be “I dare her. If she does, I will own her business. Those insurance companies have deep pockets.”