...Oh come on... That is utter nonsense to me, and maybe a few million others!...
Well I can see if you do not understand the word "potential" you may get confused.
If no one is working then that means there are more people that could be driving, ergo more potential drivers.
...Of course there are more cars on the road with people driving to those stores.
I don't imagine those same people would be driving aimlessly around in circles if the stores weren't open...
You understand that people use cars for more than just going to shop.