Well, I think they do. Everybody knows that the grocery store and gas stations only have food and gas because the trucks arrive every day. There might be a few welfare types who think it comes from the YMCA down the street, but . . . .
It would surprise me if even half know the general distribution chain, let alone some of the specific “choke points”. Having been in agriculture/horticulture for the past 25yrs (retired Farmer), I’ve met a lot of astoundingly “unaware” people.
Around here, there are massive warehouse supermarket dry-distribution centers, similar to this one in FL, but once the roads are closed, the stores etc run out quickly.
http://marcobay.com/wp-content/uploads/2012/06/Publix-Dry-Warehouse-Exp-02-7-19-12-660x438.jpg