I work in the front end, and today I was scheduled to be off at 4:00pm, but no one let me out until 4:10pm. (Managers have to send someone to come in for you or tell you to turn your light off, etc.)
If the clock strikes the time you're "supposed" to leave, is it technically job abandonment if you just leave? Sometimes if it's a few minutes past and I still haven't been let out, I'll give my manager a call, and often they will say "just wait, we will send someone in for you" or very occasionally "just leave."
Even though the difference is only a few minutes, it feels kind of degrading. Why not just schedule me until 4:15, then?
Why complain about 15 minutes? Take the extra pay when you can get it. You didn't make it sound like OT.
Read your union contract. In my store: As a department head, I can make my coworkers stay 2 hours OT past the end of their shift mandatorily if I need to. But, I need to let them know an hour before the end of their shift. I will let them know at the beginning of the shift if we are short handed. If they leave before the work is done, it is job abandonment. I haven't had to force anyone to stay very many times.
If you want to find yourself scheduled 12 hours a week, try leaving at your scheduled time after they tell you to wait another 15 minutes. Or, file a grievance for being forced to stay 15 minutes over without being told an hour before the end of your shift. Some contracts it is 2 hours before the end of the shift.
It's not degrading to work 15 minutes past due, no matter how tired you are. (and this is coming from someone who hates working for a long time) Fact of the matter is, you need to take responsibility and show some support for your store (and be a courteous employee.) If it's really busy and there is no one to cover for you for a small amount of time then cover for those 15 minutes. But I mean that's all up to your manager. Flag them up, call them over or service them.. do whatever you need to do. Usually in my store my manager will just take over the register if they have no one else. But I mean.. If that's not an option you should stay. I'd say no longer than 20 minutes though..
Not sure if it is allowed for a manager to keep you over or not, without asking if you can stay beforehand. But I have often stayed over a little bit if possible after I was supposed to leave. Rather getting farther along in the bread slack out or packaging up cookies and so forth, til someone comes in after me. I just consider it part of the job at times.