My experience in the US, across the US, is not consistent with your experiences (possibly in Asia?)<quoted text>
Maybe it's a regional thing but I've always found Walmart employees to be helpful and courteous. Their stores are, every time I've visited, clean, well-organized and well-lit. The merchandise, while inexpensive, is the same merchandise being offered in other discount chains such as Target, Ross and KMart. In rural areas of the US, they have brought the consumers choices and savings that were never available to them in the past.
As for their employment practices, they are the largest private employer in the US by a pretty fair margin. That's a benefit to an awful lot of employees. True, they aren't the highest paying jobs in the US but they aren't the lowest either. Many people in the food services industry are paid significantly lower than Walmart employees.
There are major differences in products between Target and Walmart. Walmart has their own specs. Home Depot works the same way, though maybe a little less anal. I.E. the same brand will be inferior when bought in Home Depot (or Walmart) than in another store.