Imagine, our premier neoliberal on this site admitting that supply side economics is a failure.
You aren't making any sense. This paper is essentially reporting findings that food deserts exist because of the lack of demand in those areas.
This proves you created a thread about a paper you either didn't bother to read and/or are not capable of comprehending.
None of the analyses support any such in conclusion.
In fact, none of the analyses support the thread title or any of the pseudoscience causal conclusions that the authors make.
No causal conclusions can be made, because the data is purely correlational.
They take 2 uncontrolled events (a new store entering a neighborhood, and families moving to another neighborhood), and look at change in grocery purchases from just prior to the event to about a year afterward (few people are in the study more than a couple years and many drop out in less than 1).
Eating habits are the result of a lifetime, with childhood and early adulthood years being most critical. Thus, any effects of "supply" are not merely on immediate purchases, but all future purchases. 20 years of living in a low-supply area will alter eating habits until one's death. For the same reason, any change in that supply will have a very slow delayed impact that is reduced depending on how many years the purchaser has lived in a low supply environment.
IOW, what the article is calling "preferences" and "demand" are the eating and buying habits created by a lifetime of living in one' environment, with the supply of food types being a key aspect of that environment.
The data do not allow them to test "supply" explanations against "demand" explanations. Rather they are pitting short-term effects of immediate supply against the cumulative long-term effects of a lifetime of supply + any possible demand differences. Plus, unless your going to make the assumption that poor people are born with different taste receptors, most of the "demand" differences are the direct and indirect result of income differences (including whether mom is home to cook meals).
A side note, they only studied groceries with UPC codes on the packaging, and thus did not include fresh produce or other items bought in bulk like grains, etc.. Fresh produce is healthiest and most expensive of food items and the least available type of food in poor areas.