Rarely, but:

• if whatever needs to be done actually requires the manager (refunds or such)

• if the person you've been trying to resolve the issue with is being obstinate, dismissive, or rude

• if something actually illegal is occuring (i did this once when I noticed that a gas station was charging more than their listed price on the sign, guy immediately fixed it and comped me my fill cuz that's super illegal)

• if workers are jeopardizing safety of other people. Don't tell the worker to stop, get a manager to do it and note that they're doing something unsafe.

And, most importantly:

• when you catch an employee smoking a joint outside and they refuse to share