The vast majority of Japanese vending machine sell drinks. Both cold and hot drinks are available. The great thing about Japanese vending machines is the number of non-sugar drinks that are free of artificial flavor and color.
Go into any convenience store in the United States: most of the drinks have sugar or artificial sweeteners designed to trick your brain into thinking you're getting sugar. Often the only natural, sugar free beverage available at convenience stores (outside Japan) is water.
Most Japanese vending machines have at least two or three varieties of sugar free tea. These teas are (typically) free of artificial colors, flavors and preservatives. They're also full of healthy compounds naturally found in tea.
Japanese convenience stores also offer a variety of sugar free teas. Most have at least a dozen varieties (green, oolong, mix teas, western teas). Many have more than a dozen varieties of (sugar free) green tea alone.
Japanese consumers prefer sugar free, natural beverages. It's one of the reasons Japan is the thinnest nation (of G20 nations).