This will be a myth, otherwise you're paying a manager's rate plus a low-level employee's rate for every call. It's likely what they tell the employees to put the fear of god into them.
My money is on Apple recording every call and having the managers listen into the odd one here and there, and if there are specific issues on a past call, the recording is there... just like any other large call centre.
Many managers think fear works to improve stats.
But I did get hold of their official expected call time list and after that my stats were perfect, plus I trained up other staff in how to meet management expectations.
There's a good reason Gateway got a reputation for extra bad customer service.
The "last straw" for me was when they essentially forced techs to sell hardware. Techs would lie through their teeth (oh, that BSOD is because you don't have enough RAM) and of course management blindly looked the other way.
That's basically just me spitballing the closest thing I could imagine to that, and I doubt they're doing either.
I wouldn't be surprised if they do run a whole lot more quality assurance checks on new reps than tenured ones, but that'd be pretty normal.