mdginzo wrote:
I would think it's the amount of sugar that matters and not yeast, no?

That is more than possible and probably likely.

Actually,

With Root Beer you're usually adding a lot more sugar than you need to
create the right level of carbonation. Dry Root Beer doesn't taste very
good.

The Root Beer is usually very lacking in nutrients, so using a small
amount of yeast is a common technique to get them to quit at the right
time - before they consume all of the sugar. The pressure also helps
them to give it up, but really you need to crash cool it at the right
time and keep it cold to prevent problems.

IMHO, glass bottles are a hazard for sodas. I use 2 liter pet bottles.
It prevents glass grenades and you can tell when it's carbonated
properly because the bottle will get very hard.

Andy