Other than inventing the scale-based supply-chain-squeeze modelof retail, which must go down as one of the great business innovations of all time, Wal-Mart is hardly known as a foresight-based player.
As a business model, there is a lot of inefficiency built into the supply chain and replenishment process for these street vendors, since they reside a few notches down in the distribution system from the regular brick and mortar merchants with whom they compete.