Instacart thrived on price-insensitive markup-insensitive Whole Foods crowd. Remains to be seen if they can convince the price-sensitive coupon-clipping clientele to pay the delivery fee and disregard the random product markups within the app. The average check also drops significantly at the lower end of the market - a dude stopping at 7-11 for a bag of chips, a Big Gulp Slurpie and a lotto ticket is unlikely to be their prime customer in terms of unit economics.