I'm fairly certain shipping and warehousing frozen food in bulk would be more efficient than shipping containers with fresh produce going to each and every grocery store several days a week.
Sorry but nobody in these comments understands the food value chain. Most foods require very specific temperatures and handling. Even if you transport them right, the actual storage and routing of food varies widely. There is often no location to store food properly intermediately, so diesel trucks are kept idling to keep the food in a place with the right environment. But it varies greatly depending on where it's being sold and what their logistics chain is, in addition to what market they're serving and thus where they're sourcing their food and how they're picking it.