I can't speak for the rent but from what I was told the setup (machines) is very cheap, as are the ingredients like you say. I'll also go out on a small limb and say food businesses with predominantly foreign student workers tend to have a history of underpaid cash wages. My wife was offered $6 an hour cash in the early 2000s at one place in Sydney, I think she was 17 but still that's way too little.