Be a Card Carrying Member
I see this far less than years ago but there are still some who ask for dive equipment and/or tanks without any proof of certification. Some have simply forgotten their card. Others have never had one but wherever they had been diving, allowed it.
Some of the certifying organizations have a system where proof of certification can be found through an online system. Others do not and that causes a problem. Some divers argue that they have been diving for decades and others say that the place they were at last year never checked.
Perhaps this analogy will help better understand why showing your certification card is necessary. You show up at XYZ car rental and tell them you don’t have your driver’s license. They say you can’t rent a car. You say you have been driving for over 35 years. They say you still can’t rent a car without proof of a license. You say the ABC rented last year and you showed them your license. They say you still can’t rent a car without proof.
I don’t know anywhere that would rent someone a car without a driver’s license. It is very simple. If you want to drive or dive just make sure you have your license.