The technology of vending machines has advanced significantly since the days when 20p could buy you a shot full of pale brown silt-water. As office business grows and companies increasingly find themselves wanting to save money wherever they can, they are constantly trying to offer their employees an obligatory and fair amount of variety. Vending machine makers are competing for this growing custom viciously, and exploring ways to make their machines ever more efficient.
Vending machines of the past were often regarded as flawed because of the drinks they offered being weak, their lack of choice, and the high risk of ingredients tainting other flavours. The former was simply due to the quantity of specific ingredients being increasingly modified by the operator to drive down costs. The reason for a lack of choice was likely because of a general lacking in technology compared to now (as well as the fact that these were developed at a time before fair-trade and green teas were mainstream). Ingredient cross-tainting may have happened because ingredients were added to cup in the machine and through the same mechanisms and tubes.