It’s mostly a cultural preference... Rice works as well as hard red wheat as far as calorie density goes and in the short term that’s all that really matters f

It’s mostly a cultural preference... Rice works as well as hard red wheat as far as calorie density goes and in the short term that’s all that really matters for adults. Rice also has some advantages as it’s more versatile in terms of cooking and taking flavors. A few cases of Minute Rice, a small camp stove and a variety of seasoning packets would be a win over a large bag of wheat. Longer term wheat has a higher protein content and has an advantage that it can be sprouted to increase vitamin content but you would need to be in pretty dire straights for that to make a difference. Neither wheat nor rice have enough fat content needed for long term survival. Neither wheat nor rice will sustain toddlers without a supplemental high quality protein source like milk or eggs.