They are only restaurants in name. Also I've noticed that these kind of "restaurants" are also appearing in Western food delivery apps too where the price + delivery is actually cheaper than buying from a physical restaurant, I once experienced this buying shawarmas on a food delivery app.
Taco Bell and Pei Wei leap to mind.
It's like they have a grid listing all their few ingredients and constantly try to figure out new ways to combine them into different products.
> With great fanfare Monday, Taco Bell unveiled the Grandito, an exciting new permutation of refried beans, ground beef, cheddar cheese, lettuce, and a corn tortilla. "You've never tasted Taco Bell's five ingredients combined quite like this," Taco Bell CEO Walter Berenyi said. "The revolutionary new Grandito, with its ground beef on top of the cheese but under the beans, is configured unlike anything you've ever eaten here at Taco Bell." The fast-food chain made waves earlier this year with its introduction of the Zestito, in which the beans are on top of the lettuce, and the Mexiwrap, in which the tortilla is slightly more oblong.
http://www.theonion.com/article/taco-bells-five-ingredients-...
The trigger to act commonly occurs when a key ingredient is hit with a supply related crunch. Avian flu just tripled the price of powdered egg whites? Guess we're using another binder for our ToasterOvenPastryTart. Another popular alternative is to stealthily decrease portion sizes.
https://www.sustainweb.org/jelliedeel/articles/dark_kitchens...
https://www.theguardian.com/commentisfree/2018/oct/09/dark-k...
Articles such as the ones you cited talk about the stifling "windowless boxes" but restaurant kitchens have never been windowed comfortable places. At least in the UK these kitchens are subject to the same hygiene and labour laws as any other place where food is prepared. They seem to want to imply that "dark kitchens" flout these laws but I've yet to see any evidence.
Or the materials cost is low, the unit labor cost of prep is low, but the unit labor cost of handling in house transactions and service is high, and in-house service and takeout are charged similar prices because having separate prices posted in the restaurant depresses in-house service volume and takeout unit profit without improving takeout volume to match.
(I suspect it's a little of this plus some investor business-building subsidy.)
At the end of the day, though, many of those users will churn. I'm happy to pay when VCs subsidize my orders...sounds like a cooked meal + delivery costs less than what the restaurant is paying in food costs. The unit economics of that model are not sustainable.
Is it sustainable? of course not. Does that matter to the people who want ALL of the money, not just some of the money? of course not.