Turn off 'guest contributor viewed x file' notifications

Hi everyone, I have had a strange but pretty insistent support request from a User. They are sharing links to files to external users via anonymous links. Their auditors have told them that even though SharePoint displays 'guest contributor viewed x file' and the time they viewed the file, this is not anonymous...and that google drive doesn't do this. The auditors are not happy with the privacy and went them to send files individually on USB sticks!

I am correct in thinking that there is now way of finding out who guest contributors are and that they remain anonymous? and also that there are no ways of turning off notifications that guest contributors have viewed or edited files?