I can tell you why, as no one here seems to have used these. These are rooms of food items with no workers. Say 10 fridges and other items like apples, bananas, coffee machines microwaves etc sitting out. You walk up, grab what you want, use what you want and then check yourself out. It would be wrong to sell any user data but they did this because they were losing money trying to staff lunch rooms. It costs less to ditch warm/cooler food, and rather balance food loss off these items who know they are being filmed and will likely be expelled from the college for stealing. An example woukd be Gulf Coast State College

Instead of thinking vending machine, think food court with self checkout. (Saw this both in a FL colllege and also had this at a private company in TN)