I agree they're mostly a waste of time and money. But I've only really had them when there's just me eating them. I can see the value if you're feeding teens and go somewhere like Greggs - they'll demolish pasties and cakes as part of their lunch the next day I would have thought.
Supermarkets, you risk getting a load of salad on the turn that you can't do much with unless you have a use for a gallon of lettuce soup within the next day or two. Supermarket bakery bread mostly isn't worth the freezer space.
Chain coffee shops are so over-priced that even at the TGTG price it's hardly worth it. I got a Pret one in the hope of getting a nice salad but instead got two sausage ciabattas that each had one and a half cheap crappy sausages in and a couple of cheese and ham paninis that had a scraping of ham and cheese in. Nothing nice and I could have made them myself for less - I don't count that sort of assembly as 'cooking' that's worth paying others to do for me. I also don't eat sandwiches by choice and don't like bread once it's been frozen unless it's toasted so not food I really want to eat.
The sushi/noodle type places aren't too bad, but I usually find that I'm spending the money on a few items that I wouldn't have chosen when instead I could spend the same on the one thing I do want.
Carveries are hit and miss. I've had one where I got a decent amount of meat, roast potatoes and veg that was enough for two nice meals. I also got another one that was a scraping of cauliflower cheese, few badly cooked carrots and a giant Yorkshire pudding - I complained about that one and got a refund.
I have an Ikea in walking distance that's quite good - for £2 I get enough meatballs and chips/mash for 2 small meals and you generally know that's what you're going to get.