Couldn't the waiter just switch your seats without the manager coming over ? Does the manager stand around the entire time watching everybody ?
Yes, the restaurant is essentially one small room, and the host and the manager can see all the tables at once.
As we've probably all experienced in the context of airports, hotels, banks, government agencies, etc. some personalities like to wield whatever small amount of power they've been given like they're absolute monarchs and make a show of it from time to time. This manager was one of those personalities.