Why are products more expensive in poor neighborhoods? If there were real profits to be reaped, certainly stores would be moving in and enjoying high profit margins rather than leaving.
The answer should lie elsewhere and it does. Cost of doing business in those neighborhoods is very high. Vandalism and robbery jack up insurance rates. Companies don't want to deliver there because they don't want the risk, so they charge more. Shoplifting expenses must be spread across all product actually sold. If the place offers loans, they must deal with very high rates of defaults. You can't squeeze blood from a turnip. If someone doesn't pay for that car, you have to repo it, but there's a decent chance it can't be found or that you now own an unsellable car or that it was messed up, but there's no way of actually getting any money out of the responsible parties.
Finally, let's say I put a store in a nicer part of town only 15 minutes away. I get less vandalism and basically zero robbery. I get less shoplifting and lower insurance rates. I can keep the same profit margins as the guy in the poor neighborhood and still offer significantly lower prices. Because it's reasonably close to the poor neighborhood, I even get their business without all the extra risk. In the loan market, less risky clients means I can charge less interest and still make the same amount of money and have far less overhead tracking down people and things.
The real tragedy here is police. Poor neighborhoods and police don't get along. Police view everyone suspiciously (why wouldn't they when most dead and injured police show up in those same neighborhoods?). Likewise, the people living there don't trust the police because the police treat them as criminals (and like it or not, someone somewhere is always going to make a mistake that starts this downward spiral). This isn't even a race issue. Police and the poor have had this relationship going back as far as you can search no matter the race (or races) involved.
This problem could be fixed with education, but the average criminal and average police officer both have below average IQs (with it being ruled in the US that it is perfectly legal to reject police officers who have an IQ that is "too high"). If everyone in a poor neighborhood were properly educated, it would cease to be a poor neighborhood in a very short amount of time, but our education system is only interested in lip service (another problem in itself).