Tea refers specifically to a beverage made from the leaves of Camellia Sinensis. I won't go into the finery of the etymology of the word, but the word tea comes from the Amoy tê or Cantonese chàh both referring to the camellia sinensis plant. Without this root, we would use some different term to refer to herbal infusions and steeped drinks.
My point is you can't have herbal teas without having actual tea, therefore its logical Randland has tea.
As it applies just as much to just about every word that comes out of their mouth.
Simply put, 99% of all teas I can remember them talking about are very clearly herbal in nature.... But like Yunalesca said, "Tremalking Black" sounds "teaish"... Though even that could easily be an herb...
Sadly I can't really remember any trader talking about selling any "tea", as that would probably be the simplest way to answer the question.... Meh, I think I'd just go with "Yes they have "real" tea, they just don't care about it's "realness" much.", because if they did, then talk of the trade of it, what with how often people drink tea in the books, would of likely been a lot harder to miss.