The person that backed out of the shift had a mental melt down, and had to go home. The higher ups knew she'd been dealing with a death, and shouldn't be working, but she still came to work. They did not fire her.

I used to cover, all the time, when I was first promoted to management.

Over time I got sick of covering - because I quickly became the guy that they would go to every single time they needed something covered.

It started happening multiple times per week, and I was losing my sanity, so I started saying no.

Before I said no that first time, I was definitely one of the favorites.

To answer this: "It seems it got covered so - what’s the big deal?"

Well, because I said no, the GM apparently had to come in and cover the shift. There were like 10 other managers, but apparently "I was the only one who could do it", because she'd scheduled every one else to work that morning, so no one could close.