re: When you eat out, do you know what iced tea you are drinking?

I would say offer both sweetened and unsweetened tea options.

There are people like my wife who will like to make a half-n-half, at place like Zoe's or Newk's, where you serve your own tea, and can make it half sweet and half unsweet.

ETA: make this an option if not self serve and it would only come from the kitchen