One thing to keep in mind is:
Standalone products sold for use as a human-usable sweetener are going to be different than industrial uses.
The majority of artificial sweeteners happen to be significantly more potent by weight than normal sugar. As a result, nearly all of them are mixed with some sort of filler (usually dextrose in my experience) when sold as a "table sweetener". This is to allow the consumer to have any hope whatsoever of measuring them out in a consistent manner. Even with the fillers, they're significantly reduced in calories compared to sugar.
Splenda, Stevia, NutraSweet, they're all mixed with fillers when sold as a consumer-usable sweetener. These fillers aren't present in "industrially-produced" products that don't need the fillers, like soda off the shelf.
As another example - aspartame has as many calories per unit of weight as sucrose. However, it's 200 times sweeter than sucrose, so the amount used is so little that the caloric content of a product with the same sweetness is negligible. Think of a 12 ounce can of Coke - normally 33g of sugar, but only requires 0.16 grams of aspartame. For Coke, this isn't a problem sine they mix hundreds if not thousands of liters at a time, so the amount of aspartame used is easier to measure out - but imagine trying to measure out 0.16 grams of aspartame as a user!