I'm guessing the advice is due to possibly longer power restoration times if there is an issue at the plant with fewer staff available. It's not a nuke plant, if that eases worries.
People sick.
People taking care of sick people.
People taking care of little kids (schools closed).
People afraid to get sick.
And with the Walmart hours, made me think of people taking the bus into work and not wanting to be on a bus and get it.
At some point when neighborhoods are put on “shelter inside” that will also limit the number of workers.
Our little electrical substation at the end of the block got some huge upgrades after 9/11. What of the neighbors that works for an excavation company bid on it (they didn't get it). He said it called for expanding the facility 6 stories underground.
They had a lot of dump trucks going in and out for a long time (all summer?). Other than a double gate and thick wall at the entrance, another fence around the existing fence, and an additional tower with lots of antennas, not much has visibly changed on the surface. So the story of everything added on underground makes sense.
I'm guessing they weren't planning on this type of threat to the system.
Oh - that wall at the entrance. It has “decorative” openings in the wall sort of scattered about. I think they are to be used as gun ports. I'm guessing that the place is now some sort of secure bunker for electrical and communications.