Gas is one of the few commodities where you don't know the final price until you finish pumping. The most the small pumps can do is get an authorization for $1.00; customer pumps gas. If the customer exceeds their limit after the pumping finishes, they've already got their gas, and there is a delay on the small pump for recovery of the cost of the transaction. If the customer has gone over their limit, they're hit with fees, etc, but there is a delay before the gas station is fully reimbursed.