I think you have it right. The key to understanding this is scale. What might be seen as a vast cornucopia for a family of four is insignificant for the thousands, possibly millions, most states have to worry about. Get to the national level and your vast larder doesn't even register. In the end any family, or even community, supplies are just not worth the time, trouble and diesel fuel to go get them.

A community of any significant size will be looking at major stockpiles. Like the Walmart or Costco regional distribution center, grain silos, warehouses. And if previous custom hold the people who own the resources will be compensated.

I wouldn't worry about the National Guard kicking in my door to haul away by supplies of Beanie-Wienie and generic aspirin.