Having been the client: we asked because the previous photographer sent forty images out of a full day and we had no way to know whether the other three hundred contained the shot we needed. It was not about editing at all, it was about trust and completeness.
What solved it was being shown the contact sheet. Every frame, small, unedited, with the selects marked. We could see nothing was hidden and we never asked for the raws again.
Worth trying before the argument. It costs almost nothing and it addresses the actual worry.