Mexican Coke you buy in the US is sweetened with cane sugar, but Mexican Coke you buy in Mexico is often sweetened with high fructose corn syrup.
The US uses corn syrup because the US government heavily subsidizes corn. Some Mexican producers in Mexico do use corn syrup, which is a cheap import from the US, but even here the majority use sugar.
This kind of thing happens in with other countries as well. In New Zealand you can get local coke which is sugar-sweetened or imported American coke with corn syrup. People didn't switch to corn syrup because it's better or even cheaper in and of itself, they switched because the US government goes to ridiculous lengths to make it cheap.
FWIW.
Anyway it'd cost trillions to retool for some other staple crop now.