I don't suppose the corn syrup vs sugar in regards to passover kosher is easily explainable or do you have a link? Just curious.
I *think* that any foods derived from grains are verbotten during passover. This would include corn syrup, as it is derived from corn, which is a grain.
Government regulation doesnt forbid the use of sugar, it just makes it more expensive. Coke certainly has a much lower profit margin on the passover-cola than on their regular stuff, which is probably why they dont sell it year round. There are plenty of small soda manufactures that use real sugar, they just cost more.