There is no doubt Tesco etc are in it for the money, and you should approach the multiples with caution, and get independent advice from someone who is experienced in such things.
I'm sure the Tesco deal with O'Hara's is good for O'Hara's as it's not an exclusive deal and O'Hara's are dealing with multiples long enough to know how to handle them.
A family member was in a similar business and their product had a 10c gross margin for them in the multiples, while it had a 50c gross margin in a corner shop, yet the multiples sold so much that they decided to do away with the supplying to corner shops altogether. I said gross margin as costs of delivering to and supporting the smaller shops was far greater than doing a few bulk drops at the warehouses of the multiples.