It's not clear who gets the refund here. If the scalper, then he has no risk, and earns both the money he sold it for AND the refund of the original fee. Win! This is also likely the only refund they can do since they don't have the credit card number of the person who bought the scalped ticket.
If they refund the final purchaser, then the scalper still makes his money and the purchaser loses the amount above the face value.
In both scenarios, the scalper makes his money, or even more than he would have otherwise.
If the final purchaser is aware that their high-price ticket could be nullified at the door, it removes motive to buy in the first place, leaving the scalper with hard-to-move tickets.
If they refund the final purchaser, then the scalper still makes his money and the purchaser loses the amount above the face value.
In both scenarios, the scalper makes his money, or even more than he would have otherwise.