The question is, “Are you really in that big of a hurry that you cannot boil water for a cup of tea?” Developed in the 1930s instant tea did not find a commercial application until the 1950s. Soluble teas are certainly convenient, and there is heated debate about whether that is worth sacrificing the flavor nuances of a good cup of tea.
India and Sri Lanka are the two main producers of soluble tea. Since the appearance of the tealeaves is of absolutely no consequence with soluble tea, harvesting tealeaves for this process is extremely efficient. To make soluble tea, generally a concentrated brew of black tea is dehydrated. The brew is made from processed tealeaves, fermented tealeaves that have not been dried and tea wastes. It is then concentrated under low pressure, and the concentrate is then dried to a powder by one of three methods, freeze drying, vacuum drying or spray drying. Very low temperatures are used to minimize the loss of aroma and flavor.
Soluble tea, or instant tea, is popularly used for making iced tea, though it can make a hot cup of tea equally well. Along with freeze dried or instant coffee, instant tea has found a loyal following. Frequently instant tea is flavored with added flavoring like lemon, honey or fruit, and it is even blended with powdered milk. These products come in formulations for either hot or iced tea, and they have remained popular because they are easy to use.
While a real tea connoisseur would likely turn their nose up at a cup of instant tea, for some it may be the better of two evils if the choice is instant tea or no tea at all.