Part of why Brazil uses sugar cane is because they have the right climate for it. Most of the US's sugar is from domestic sugar beets.

The other big reason is, they had all these acres of cane when we clamped on the big mungo tax on sugar imports to protect our domestic growers. When that happened, thier economy took a solid kick in the jimmies, which made gas an out of reach item economically, and with all the sugar going to rot in the fields, they solved the problem themselves.