Thesis: The "realistic" aesthetic across several genres and mediums is promoted by Capitalism as part of its effort to commodify art by mitigating the impact of creativity, increasing the impact of technical advancement (i.e. capital), and providing a means for a work of art to be judged objectively rather than subjectively.
Originally a break with prior artistic styles by returning to a certain style of realism and naturalistic portrayal and framing, Modernism was the first art style to get coopted in the birth of the advertising industry as a thing separate from just doing business to make things and sell them to people who want them. Simply because it was the popular style at the time, it was what artists hired to do just happened to be doing.
This intersects with the contest of East and West in the form of capitalism vs. socialism, and during that period, the cultural competition between the blocs took form in trying to look the most advanced and shiny and forward looking. Art was one part of making this real for people, and both major superpower governments sunk big incentive resources into producing art to represent their ideologies attractively. For a long time, this was in a similar modernist style in both cases.
The next movement in art that hits here was surrealism leading into postmodernism. These were reactions to the great wars of the 20th century and the way the promises of modernity seemed to be failing and false. They also were reactions against the way modernist art was being used for advertising and commercial crass interests. Tension about the cultural messages in art on either side took shape in such conflicts as the McCarthy investigations and Andy Warhol painting Campbell's soup cans in critique/contemplation of his own every day consumption of the product.
The phenomenon that led to this post being requested and written came out of these conflicts, when some theorists from the University of Chicago successfully used national crises in other countries to wedge open markets and implement deregulation. This shock treatment became the basis for neoliberalism, which is now the hegemonic political economics of the world. Neoliberal ideology can corrupt and co-opt any artistic style, and has weaponized cultural conflict between its recuperated forms of modernist, postmodernist, and even post-irony anti-capitalist sincerity and vibrant iconography.
So in answer to the original request, the way realistic art is commodified in comparison with photographs and through machine learning models, is a combination of diverting energy through a bullshit culture war of realism vs other styles, devaluing labor by framing technical image creation through capital assets as disconnected from that labor (which is a lie), and continually recuperating the creativity of people who embrace the aesthetic through that side of the spectacle. It's part of the capitalist realism written about by Mark Fisher in his book of the same name, how there is portrayed to be no alternative now that the Soviet Union is gone. Still, this "common sense" is coming under more and more strenuous question. It may be easier to imagine the end of the world than the end of capitalism, but more and more people are willing to try the one to get the other since the climate-death of the world and other disasters (trans genocide by reactionaries, women's rights stripped to nothing, more cops killing more Black folks, etc.) are guaranteed results with capitalism still around.
