from the Guardian
A Russian cafe chain called Ziferblat has opened its first UK store in east London. It provides tea and coffee and Wi-Fi for nothing – but it's 3p a minute to sit there. I know. Genius.
But in Shoreditch where this is based, this makes sense. The biggest chunk of a cup of coffee in that area is the space you're occupying drinking it. You compare the price of a coffee in central London with the price of a coffee in say, Swindon, and there's a bigger difference in price than the price of the coffee beans (about 20p of the cup)(1). The extra rent is being added into that coffee.
If someone has 2 coffees in an hour instead of 1, all that's really costing a restaurant is in coffee beans and maybe milk. Staff, rent, heating, lighting are all fixed for the period. They're sitting at the same table, denying it to other customers whether they drink 1 or 2 in the same period. By charging for rent, it's charging based on the most expensive bit of the coffee being drunk.
