"I don't fit in a generalisation therefore that generalisation is not true". At the same time, not sure we have the data to back up the original argument. Personal anecdata? People around do expect to find everything all year round, and they get mad if they don't.

What are you supposed to say if you read a statement that includes you in a group you don't belong? That's why it's important to be more precise instead of saying "customers" in general.

It’s obviously a generalization. If you don’t fit that description then they’re obviously not talking about you therefore nothing has to be done. Why would you have to say anything anyways? Who are you?

"personal anecdata" or not, what he is saying is market demand. If you offer cavendish that taste like mashed potatoes, you won't see that persons money. Mine neither. Fact.

Agreed, I think the statement should be "supermarkets want to sell us products all year round".

An experiment: walk into a diner in mid-winter and ask for a BLT.