Tokyo's streets are characterized by a plethora of vending machines-dispensing everything from soft drinks, candy bars, and cigarettes to magazines, personal toiletries and beer. Unlike other major cities such as New York and London, virtually every downtown street corner seems to have at least one vending machine. Relying on the concept of opportunity cost, explain why vending machines are so prevalent in Tokyo versus more traditional purveying mechanisms such as newstands and grocery stores.