This is the thing @lotsofpulp that everyone else seems to be missing. The amount of your income that is available to spend on goods after all of your other fixed expenditures. This has been so solidly tracked in terms of stagnant wages and applies to the SMB in the area as well.

Open a grocery and try to staff folks and have consistent supply of goods. Deal with shrinkage, spoilage and inefficient supply chains.

Meanwhile Wal-Mart (or other MNC) has a ton of capital, their employees are on social services and the cost of their goods for this town's store is in a negotiation of not one store but thousands.

People spend what they can. The middle class shows us this in their consumption of target over walmart and other such brand divides.