You're missing the point: "Caution -- Coffee is Hot" is the short version of "We got sued because some moron dumped hot coffee in her own lap so now we're putting a label on our coffee so that the rest of you morons out there can't claim we didn't warn you when you do the same thing." You can see why they went with the other one, they'd have to have made the "small" coffee 20oz. just to fit the full version.
