I’m sure your theory is valid, and I know from working in call centers that yes, they do monitor/record calls to make sure the agent is doing what he/she is supposed to do, and doing it right. Quality control people do work with those calls to find out who needs more training on something or who just needs to be let go.
Recording would serve multiple purposes, so it’s not either/or.
I had a guy call about adding some insurance to my credit card t cover household appliances. He never sdaid the call was recorded. I told him send me some info and I’ll evaluate it. I never received the info but they started charging me for this service. I didn;'t even notice for a few months, thinking the chanrge as for something else.
So I called up and they said I must have agreed tot he service. They played back the call, and siad that proves I asked for it, so they wouldn’t refund my money. I cancelled the credit card shortly after.
So there’s another motivation for recording calls.