To your third point: I think there issue here is that wealthy people are also more likely to buy different products. I got example only buy Jersey milk and past

To your third point: I think there issue here is that wealthy people are also more likely to buy different products. I got example only buy Jersey milk and pasteur raised eggs. Because of that alone I have to stop either at Whole Foods or a similar local chain. I but most other staples at Costco. Stopping at one more store to save a small amount of money most of the time isn't worth the hassle.