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.
While price pressures have eased for most commodities, food inflation is still accelerating at a worrying pace due to inefficient storage and distribution facilities for farm produce, which lead to regular supply shortages.
But even those who want to sell E85 face problems just getting it to the pump, because there isn't a distribution system in place for ethanol like there is for regular gasoline.