You watch them the entire time. It's not like they are walking off with your credit card. You pull up, roll down your window. The attendant comes over. You say what you would like: "$20 regular cash, fill it regular cash, fill it regular credit".....whatever. The attendant then walks about 2 feet away, puts in your credit card (if you are paying by credit), puts in that the machine should stop at $20, unscrews your gas cap, puts the nozzle in, and starts filling the car.
He then goes to another car, leaving your card in the machine, where you can see it the entire time. When the amount of gas you wanted is in your car, he then removes the nozzle and hands you your credit card and receipt. Unless he has an extreme photographic memory, there is no way he can copy down your credit card number. You see him the entire time he is pumping your gas.
It's the same with cash. If you are only getting $20 of regular, at the end when he is done filling up your car, he comes to your window and you hand him $20. You can usually also do this at the beginning too.
I think i'm going to video tape the next time I get gas just to clear up the confusion. And once again, it's not that I can't or refuse to pump my own gas, it's ILLEGAL. The attendants literally stop you from touching the pump. Sorry, but i'm not willing to battle and go to jail over the right to pump my own gas. If I so desperately wanted to, I would drive over a town and fill up there. It does not make me any less of a woman because someone pumps my gas for me.