Should the government subsidize with grants or tax incentives the building of, or improvements to, grocery stores?

First googlemap the following itinerary in Baltimore, MD:

1. 2801 Smith Avenue
2. 3308 West Strathmore Avenue
3. 6601 Reisterstown Road

When I was in graduate school, I had a third floor apartment in a private home on Strathmore (you can actually see the house if you go to street view). From my apartment I had two easy options for groceries--the Pantry Pride at Greensprings Shopping Center on Smith Avenue and the Pantry Pride at the Reisterstown Road Plaza. The Plaza was marginally closer, but it was trivial difference, especially when you consider that the traffic at the Plaza was busier. But the quality of the fruit and vegetables was always markedly better at the Smith Avenue store, and that's where I typically went.

How to explain the differences in the produce departments of two stores in the same chain, located only two miles apart? Could it be that the population that lived around the Plaza was poorer, on average older, and blacker (and probably less likely to have cars) than those who lived in the leafier Smith Avenue neighborhood?

Which leads to government programs in Philadelphia and New York to intervene in the market to subsidize grocery stores in selected areas [["With a little help, greens" NYT 16 Jun 09]. How could such government intervention be justified? Or can it be justified at all?