Traditionally Kiosk a.k.a. Periptero licenses were awarded to the Anipirous or disabled war veterans of Grecian conflicts and are still propagated through a prize winning Byzantine inheritance system.
What customers do is: open the fridge door, grab the refreshments you want, walk over to the periptero and pay the attendant. Do not ask them to get it for you.
Water costs 1 euro and 50 euro cents respectively and don't pay more. Here is a typical outdoor kiosk or periptero cooler, its a free standing refrigerator and there on the bottom right shelf; the small water bottles. Click to see larger
On the other shelves one may find, and this depends on the periptero owner I guess: fruit juices, sodas, milk, power drinks, soft drinks, beers and wine coolers too. In Greece you can order scotch whiskey or a cinzano or campari soda in a movie theater so why not beer from a sidewalk cooler?