i think this “1 carb=16g” thinking is a holdover from the days when people used dietary exchanges, if i had to guess…the exchange system isn’t really optimal in a world where you can count carbs and bolus far more precisely than you could in the past
Just bear in mind these are very low carb, but not at all low in calories or fat. So if you’re not doing a super low-carb (Bernstein) diet, the fact that each one of the cinnamon rolls is 200 calories and the same fat and saturated fat as 1/5 of a stick of butter will probably be of interest.
It’s not optimal, but it saves time and allows one to do some of the computations in your head when eating unexpected foods away from home. So I know without consulting any reference that 1/3 cup rice is a “carb exchange” of about 15 g carb the same as 1/4 of a bagel or one slice of “average” bread. (Unfortunately “average” bread is getting increasingly hard to find - slices are getting bigger and denser).