Yeah, I don't see how it's possible for all fountains to get the exact same syrup and gas concentrations. Especially with ice and temperature also being factors.
They use different sweeteners in bottled Diet Coke and fountain Diet Coke. Bottled Diet Coke uses aspartame, while fountain uses a combination (one being AceK, can't remember the other(s)).
> don't see how it's possible
It could be computerized pretty easily, it's just not.