You’ve got to be kidding me. You’re lucky that they even accept your VGC. Don’t get the attitude that they “have to” take your cards. I’ve been denied at multiple WM because of people like you.
The best practice is to “husk” your cards in the car. Don’t let the clerk see that it is a GC. All it takes is some minimum-wage employee taking to the manager and the manager can change the policy of the entire store.