The 27p range is interesting. Nobody makes money on it. All the supermarkets have to have it, they go to great lengths to make it as unattractive as possible. Look at the packaging, the blue and white "label of shame" could be made to look attractive but that's the last thing they want. Manufacturer s make the 27p range because they are forced to bid for a tranche of business. If you want the core business then you need to take on X volume of the 27p tut.
Technically the 27p range can be interesting because you are trying to make a bit of orange juice, sugar and pectin resemble marmalade, it has to be stable, safe and meet regulatory standards. Sometimes an interesting challenge. Not always though, I've a friend who's a wine maker. When he gets to the Eu 1.25 Spanish table wine he doesn't bother tasting it. It's legally wine, the lab results are in spec, done. Pack it. "Oh but it's not as good as 1996 Chateau Lafite" . No, it's not. What do you expect for Eu 1.25?
That's what I figured about not making money, although the old "value" labels actually bit the dust at least a couple of years ago. Tesco rebranded the range to bring it into line with the style of packaging you get in Lidl and Aldi. So it's no longer immediately obvious that it's a value product. I keep meaning to buy a jar out of curiosity, just to try like, but always end up chickening out. I hate throwing food away, and if I don't like it, well... Even if it's only 27p, it's still food that's been thrown away...
The same must therefore be true about the other "value" prepared food as well. I get the fact that it's challenging to produce something recognizable from a much more limited range of ingredients - you're not going to put best butter in something that's going to sell at a loss after all - but some of the other posters have raised valid points about the quality of some of those ingredients. There was an "Inside the Factory" that looked at sausages - I think they were at a place that made the Heck ones. If memory serves, they used the premium cuts of shoulder; the trimmings, fat and skin etc were boxed up and sent on to another place that made much cheaper sausages.
Value rage fruit & veg OTOH - yes, I do buy it, and plenty of it. I don't care if they're big, small, wonky etc. Fresh produce is fresh produce after all. It's cheaper because typically it doesn't meet the standards for size and aesthetics. And some of the fruit isn't quite as sweet as what's available in the more expensive ranges.
And re the wine - I'm teetotal, so can't comment, but I'd say the same about chocolate. Cadbury's dairy milk has 20% cocoa solids in it - I understand that's the legal minimum for it to be called chocolate. And that stuff isn't even on the same planet as the Green & Black milk chocolate, which either has 32% or 35% depending on which one you get. (The one with the Anglesey sea salt in is absolutely lush, btw...)