When planners map a city's grocery access, they often draw circles a half-mile wide around each supermarket and shade everything outside them as 'underserved.' The method is tidy, but it assumes that a straight-line half-mile means the same thing everywhere. In a neighborhood of quiet, gridded streets, half a mile is a ten-minute walk. In a district split by a six-lane highway with a single pedestrian bridge, the same half-mile on the map may require a forty-minute detour on foot. Residents there are counted as 'served' by a store they cannot practically reach. A recent survey asked shoppers not how far their nearest store was on a map, but how long it actually took them to get there and back carrying bags. The answers scrambled the official picture: several blocks the city had marked green reported the longest real travel times in the survey, while a few shaded blocks turned out to sit beside an unmapped corner market. The planners' circles, it seemed, measured distance faithfully and access poorly.