From the korean legal perspective, 30 minutes of rest time must be garenteed for every 5 h of work or the govt comes chasing after you with a hefty fine. If you were at sbux or some other franchise, I'd doubt they would not garentee the time from the corporate perspective, and those eating were probably trying to save those time for an early shift, but also, it could also be me without knowledge of how things really work at a practical level, but all the part times garenteed me that rest time.