Drive thru clossed

Went to the drive thru and waited to for almost 30 minutes without movement. The serving windows were CLoSsED . Wen I went in to find out inside the shop I was told there was shift change so it normal for them. I called for the manager Gloria who took 10 mins to come to me. I explained my concern and she told me it's procedure when shift changes. Please can someone tell me why u built drive thru if I have to wait tht long. There was almost 15 crew in the premises standing doing nothing