When I lived in Schertz Tx (just north of San Antonio) back in 1982, when you went to a resteaurant in Texas, instead of bringing you a water, they would bring out empty glasses and a picture of un-sweet, iced tea. It was not optional. This was the case in every establishment I went to from Texarkana to San Antonio.
Now, I cannot speak for how things are now as I have not been to Texas very often since then. But back then, it was un-sweet tea. And if you wanted sweet tea, they brought either a bowl of sugar or the sugar packets. I don't remember there being any artificial sweetner then.