I waited tables at a place that had a couple of tea machines. One for sweet and one for unsweet. They made about 5 gallons at a time and, yes, part of operating the sweet tea machine was making sure the corn syrup bag wasn’t empty. It automatically injected a certain amount of corn syrup into each batch that was brewed. My guess is that these machines are standard equipment in the restaurant industry.
BTW, I’m a southerner and prefer my tea unsweetened.
I've noticed this. Anywhere I've seen an iced tea tap next to Coke, Sprite and the other soda taps, it's usually tea syrup mixed with water and dispensed. No thank you...I prefer my iced tea properly brewed...and unsweetened, although I have been known to enjoy a southern sweet tea from time to time. :)