Like barry-cotter said, it's mostly lack of demand. People just eat unhealthy as hell. I know what you're talking about, though, with lots of places having just dollar stores or other mini-markets without a section for fresh produce. The only one I've seen doing otherwise here in Mid-South was Aldi in event there wasn't a Walmart. I like the idea of a produce truck or food truck that also has produce. It's worth trying to see what happens.

Here's your main issues in those "poor minority neighborhoods" which, having grown up and lived in them, I consider neighborhoods with very low profit, lots of theft, and a high amount of rape/murder:

1. Even they have been trained to be picky about their produce. Unless it's food bank, there's going to be spoilage from them ignoring some percentage of the produce that doesn't meet their standards. The profits of the operation must cover those costs on top of things like the truck and person's paycheck.

2. Like ice cream trucks, the truck will need to be refrigerated to reduce that. Produce is normally stored close to 40 degrees in grocery coolers. I don't know how much this adds to the cost of a truck.

(Note: Both of these issues might be addressed by having people order stuff like Instacart, they go pick good ones at a warehouse with maybe some extra cases of fast movers, and there's a limited window of delivery time in each area.)

3. The big one: the driver might get jacked with the money taken or the vehicle might get stolen/vandalized. The odds go up with the number of gangs present. The local Piggly Wiggly's and Kroger's that closed in Memphis had so much theft that security guards couldn't keep up with it. One had six. I was told some were paying for extra insurance for employees' cars that were stolen or vandalized. Then, there was gang violence with 10-20 on 1 attacks on employees that came out of nowhere. Although pretty common, I've only seen two put on YouTube. (NSFW) Here's an example of what they might face which they won't in any other type of neighborhood (poor or otherwise):

https://www.youtube.com/watch?v=yxBIVnjlKos

It stems from a mindset where it's considered fun. I don't know why there's all this speculation about environments causing it given any of them will tell you they just enjoy dominating other people. Example from that or another attack:

https://wreg.com/2014/09/30/young-men-say-kroger-mob-attack-...

So, the person running the food truck was to take on all this risk to their physical and mental health to serve folks in these communities making about no money. Most people who talk about these issues don't volunteer to do that. They usually aren't volunteering even at local food banks or donating fresh produce to them. Yet, they expect businesses to operate nearly at a loss when they can make a profit elsewhere. They also expect other people to take on enormous stress and risk their money/lives to serve people in areas with high theft and violence. I don't think it's a reasonable expectation. Given the theft and attacks like the vid, I don't think avoiding those areas is some kind of discrimination. Self-preservation and maximizing personal happiness/profit will lead to same decision for most folks. That includes minority members that usually move out of the same areas the second their finances or college situation allows.

I expect those communities to do more to get that stuff in check to lower the risk of people supplying them. Responsible folks, cool folks, rebels... all of them should take a stand against thug culture with no apologies for their unnecessary love of violence, esp against locals. Gotta pull them in other directions where they can feel like they're being rebellious or bad without that level of damage being done. Once crime goes down, you'll see more kind, but risk-adverse, folks accept low profit to invest in those areas and help them out. An example of people doing that, even more given the crime, are the Stepherson brothers (Superlo Foods) that took over some areas Piggly Wiggly and Kroger left. Walmart also operates near lots of poor neighborhoods.

https://www.superlofoods.com/about

It was also interesting bias that so much media reported the companies "creating food deserts" in Memphis with barely any treatment of the white family that eliminated several of them. Also, (IIRC) none of the well-off minority members invested in a coop, franchise, non-profit store, etc to serve the areas they came out of. Piles of minority members shop at Costco, Whole Foods, high-end department stores, jewelry stores, etc. Zero coverage of or blame for their apathy in the news. So, I call political posturing (i.e. BS) on all that while pointing out the tiny few that are actually doing something about these problems.