No, but only because it illegally coerces its suppliers into giving it sweetheart deals with lower wholesale prices, and nobody is enforcing the law to stop it from doing so. As the article explains, the reason for most of the price differential between large grocery store chains and small independent stores is that suppliers, forced to artificially reduce the prices they charge the large chains, have to recover that loss by charging higher prices to small stores.
Also, traveling to a store that's farther away isn't free. The trip has a marginal money cost and, more importantly, a time cost.