Why?
Because the stores closest to us suck.
We live close to the major American city and many--not all--but many of the workers at our closest Walmart and Target stores simply do not know how to act. They don't know how to make customers a priority and treat them with common courtesy and a spirit of helpfulness. On top of that, many of the customers do not know how to act. They trash the merchandise and make a complete mess of the shelves. Some of them aggressively interpose themselves between fellow customers and the merchandise they seek. It's as if they want to exact personal vengeance against people of different backgrounds than their own. It creates an almost dangerous environment. If you throw in a poorly lit parking lot near a high crime area, it's just simply not a good place to be.
That's why we drive 20 to 30 miles into the suburbs to encounter nicer store personnel and nicer customers. It's aggravating. But, we like to drive and it provides a nicer overall store experience for us.
Corporate trainers for big box merchants would do well to emphasize that not all cultural and racial insensitivity comes from the majority ethnicity to the minority. Sometimes, it can be vice versa. People of any sex, race, religion, or national origin can harbor prejudices against a variety of other people based on skin color, national origin, age or gender. When those prejudices come from a store employee to any customer, it's not a good thing.
It's the kind of thing that makes a customer want to avoid stores entirely and handle purchases online with the anonymous click of a mouse.