[andjd]

Note also that most soda fountain syrups also use saccharine instead of aspartame. This is probably so the syrup doesn't go bad as quickly. The transition to aspartame was driven by a study that showed that saccharine caused cancer in rats. That study had issues, but it had enough of an impact that consumers looked for alternatives. For soda machines, there usually isn't an ingredient list visible to the consumer, so that pressure to switch to aspartame didn't exist. There was a class-action lawsuit a few years ago claiming harm from the fountain formulation of diet sodas being different from the same brand sold at retail, but I believe it was thrown out.