I too have never understood pre-bottled tea beverages. you don't know what kind fo tea is really being used to make them (quality wise) even if they tell you a certain kind you don't know for sure.
They are generally really expensive;
I find them overly flavored to the point where is basically just a juice or fruit drink and the 'tea' aspects are gone.
some of them take a very loose definition of what "tea" is.
Tea is a specific plant (white, black, green, oolong teas are the same plant but grown in different manners, picked/processed differently)
Rooibos is a different plant all together even though it is dubbed 'red tea'
Maté is another completely different plant, I've heard it referred to as south american green tea
various herbal blends don't make a tea, but rather a tisane
