Magenta, lets talk about greed.
I think the food companies want you to buy more because it makes them more money.
I once worked in retail, the boss wanted me to encourage customers to spend more by buying more but all it gave them was stuff they didnt need and had to give away. Of course the boss didnt want to keep stock for too long, cos it cost him.
In retail, there is a whole sector called FMCG which stands for 'fast moving consumer goods' . Also wholesalers buy in bulk, for much cheaper, and many big box stores esp warehouses and supermarkets do bulk buying and want customers to bulk buy too, hence places like costco.
Its pure greed. In the Bible it talks about the man who stored stuff in his barn and made even bigger barns. He didnt know his life would be taken at any point all he cared about was storing all his stuff.