> caller on the phone to take higher priority than a customer standing in front of them

Oh. That triggers one horrific memory.

I was buying some bread at a nice local bakery. I wanted a few items. While three or four of us were in line, someone called in. The in-store employee pulled the last loaf of one variety off the shelf to reserve it for them.

When I complained, the manager told me that that was the correct move and they supported the decision. I suggested that polling the people who were actually in the store - actual, not just potential customers - before giving away the last loaf is probably wiser.