No one is asking for proof in the form of receipts, screenshots of the person at the podium, a signed affidavit from the presider/chair, or much of anything.
You�re fortunate never to have worked at a place where they do require proof. Good luck with your tenure application.
You are telling us that people ask for receipts for conference attendance in order to accept the cv? What happens if the conference is in your town, you live at home, and walk to the event? Receipts?
So, you expect us to believe you have to keep a drawer full of old receipts for conference attendance in case an administrator ever needs to look at your cv? I do not believe it. Of course if you want reimbursement for a conference someone may ask for a receipt. That's not about the cv, its about the money. Updating or not updating your cv has nothing to do with that.