It’s not root beer it’s sarsaparilla. The original sarsaparilla was actually invented in the American Wild West. At some point it was imported, adapted and popularized in Taiwan.
Hmm....Not sweet? I Guess as a Taiwanese , our standard of Too sweet is the standard of Not Sweet in USA xD Oh and I agree on the 仙草茶 part as I don't like it as well despite me being a Taiwanese xD