I almost never drink the American macrobrews, but I was curious about looking into this. While rice is common, corn is actually more common (especially in the form of corn syrup). Hilariously, many companies pass both ingredients off as variations of "fine cereal grains" without actually specifying what they mean exactly.

Of the 13 most popular beers in the US (rankings based on what I found in a USA Today article), three have rice, nine have corn (usually syrup), and there's only one with no rice or corn.

Rice: Bud Light, Budweiser, Michelob Ultra

Corn: Coors Light, Miller Lite, Corona Extra, Modelo Especial, Natural Light, Busch Light, Busch, Keystone Light, Miller High Life

No rice or corn: Heineken

I do think calling them barley flavor rice sake is a bit unfair to sake, which has a much more complicated fermenting process than beer. In any event, I had no idea how much corn syrup goes into cheap American beers.