There are many studies showing that night shift workers experience more mental and physical health issues than day shift workers. Obviously, some things absolutely require night shifts, such as hospitals, but not stores and restaurants. Convenient, sure, but not necessary. So in a socialist country that prioritizes the well-being of workers, do you think these non-critical 24-hour establishments would exist?
Some sources on the health effects of night shifts: 1, 2, 3, 4, 5
For stores or restaurants, there’s not much reason to have night shifts. Even many capitalist countries don’t have them. Just do your shopping during the day so people can have their sleeping time free.