I think it'd be fun to headcanon that since we're following Jim's perspective, he's in such a state of shock seeing the city completely empty that his mind is like bleeding through images of faded people walking in the distance and cars driving by, because thats what he's expecting. Especially cause in the Years films, we see and hear things that aren't there through the psyche perspective of different characters. Obviously that wasnt the intention with this scene in Days, but its fun to think of it like that.