All of them? It's not like private stores or businesses are legally required to be open at specific times. They decide for themselves when to open and how to lay out their shifts. It's normal to have some variation in operating hours between different businesses.

Individual employees don't necessarily have the option of setting their own personal hours, especially for shift work, but if there's a clear preference among the group then they have a decent chance of getting the business to adapt its hours to suit the majority.

This is ignoring certain jurisdictions which have made the short-sighted mistake of hard-coding specific hours into local employment laws. Such laws would need to be updated, of course, to reflect this or any other time zone change.