American cane sugar is subsidized, and has been protected since before the Civil War.
US manipulation of the domestic sugar market has apparently been going on
since 1812. The government also imposes import quotas on foreign-produced sugar. The effect of all this is that HFCS - made from US corn, dontcha know - is relatively cheaper, and therefore used in more products than it would be if the government weren't manipulating the domestic sugar market for the benefit of a few large manufacturers.