Yes, bubble tea is my life. I work in Chinatown, so it's hard to lose weight lol. Bubble tea, Thai iced tea, noodles, dim sum... Ugh!
I've had to make sweet tea in restaurants in the south for like 20 years of my life, so I know how to make it. I just won't DRINK it.
To make sweet tea, most restaurants use simple syrup, not straight sugar. Brew your pot (vat, bucket, jar, whatever) of tea. Mix about 2 cups of sugar into about 1-2 cups of boiling water. Let it cool - it becomes thick, like syrup. Mix it into your brewed tea, to desired sweetness. Voila. Your nasty sweet tea is ready.