Walmart used to be open 24 hours, and I would often hit it in the middle of the night, coming home after a late night work event (common for my business).

There were still a lot of people, just not customers. Late at night, the aisles fill with stacks of boxes, and there is an army of workers stocking shelves. Those people will all be replaced by robots within a decade, maybe even half that time.

Anyway, after Covid, they adopted normal hours, and aren't open all night anymore. There are a few drugstores that are open 24 hours, and convenience stores as well.