Nah, I disagree with you there. I don't think the nature of the product being sold affects my opinion or expectation of whether or not producers are expected to

Nah, I disagree with you there. I don't think the nature of the product being sold affects my opinion or expectation of whether or not producers are expected to shoulder the cost of a discount given by a middleman. For the record, I also disagree with your blanket claim that supermarket discounts are negotiated ahead of time. Some are.