I think it is because I'm sure the sugar breaks down way faster than the corn syrup. Needless to say if you're getting those Big Gulp sized drinks they deserve to be slugs
Discussion
Corn syrup is fructose while cane sugar is glucose and sucrose.
All the sugars get broken down into glucose when it goes into your blood.
I think the issue with corn syrup you can get more of it into a liquid before it solidifies, so drink makers will just put more in than they could if they were limited to other sugars