but, but, no

While I like the theory, most Walmarts have started closing atound midnight, so maybe just demons rather than only vamps

There must be no vamps where I live then bc our Walmart has windows on the ceiling and doesn't hire greeters anymore

Vampires must be invited into HOMES due to the strong threshold surrounding it. Thresholds are entities separating homes from the outside. They most prominently constitute a barrier to magic, making crossing them impossible or inconvenient to magical beings unless invited in. dresdenfiles.wikia.com/wiki/Home_threshold