I live in a large city, and even here there are no Co-Op "supermarkets" left that could be in any way compared to even the smallest "proper" supermarket.
From 1997 to 2002, I worked in a Co-Op non-food store, and in all those years I never set foot in a food store, despite getting a staff discount, because the nearest supermarket was miles away from where I lived, and even with the discount it was not financially comparable to the larger Tesco nearer to home.
I only ever look upon the Co-Op stores as I would do a Tesco Express, Sainsbury's Local, or a corner shop; as in, I would only go there for emergency items (or indeed an item), or to buy a sandwich. That's it. In all of those shops, a bottle of cheap bleach for example can be almost double what you'd pay elsewhere, and often they only stock branded goods which I wouldn't ordinarily buy when the supermarket does their own brand for less.
But even as an emergency, the Co-Op is still the last place I'd go to while I am blessed to be able to run a car, indeed I probably drive past two or three to get to a Tesco Express.
OTOH, I've had to arrange three funerals in the last 18 months and all were done through the Co-Op. I have no idea how the prices compare, but the service I got was outstanding. They couldn't have done more for us.