It's easier to piggyback on an existing behavior (keep on eating rice, but use this different kind of rice) than creating a new behavior (eat this vitamin pill).

On the consumer side, one can explain that the new golden rice is better and keeps your family healthier than regular rice. It's simple enough to be understood by people with low levels of education that the yellow one is better, and can easily be communicated to other members of the family who may not be able to read. There might be issues with counterfeit rice (dyed yellow instead of being actual golden rice), but that would be a separate problem.

In the cases where new behaviors are wanted, it helps to root them in culturally specific ways. For example, for iron supplementation, one way to increase the amount of iron consumed is to use a few drops of acid (such as citrus juice) combined with an iron ingot. This was done to alleviate iron deficiency in South East Asia.

Obviously, this was a very foreign behavior with low compliance, until they reshaped the ingots to be fish shaped, leading to the "lucky iron fish." Explaining to people that if they cook with the lucky fish in their pot, the fish will bring them good luck and health. This has led to much better compliance and outcomes.