Just the rights management issue of the training set is a tough question. Then you have to account for quality, direction and dimensionality of light, food styling, props, custom products or ingredients, the list of challenges goes on an on.
Then after the image is produced, if you're a food company, all your imagery is a kind of 'claim-based' imagery meaning consumers assume it is real and in some cases, there are laws preventing the use of fake foods in ads.
I'm curious about the implications of a world where AI stock photos are ubiquitous, but some styles of imagery are pretty far out at the moment.
Source: Spent 15 years in the commercial photo industry.