HotLine, the two-tier pricing is no surprise; indeed, I'm surprised it hasn't become more popular, long before now.
The legal price is the cash price. After all, doesn't the money itself say on it "good for all debts, public and private?" It would be illegal to charge extra for cash.
More to the point, paying with a card - debit or credit - costs the merchant extra. Sometimes a flat fee per transaction, sometimes a percentage. In return for that fee, the merchant gets some value: less cash to worry about, easier bookkeeping, guaranteed payment, etc. With the prevalence of credit card use, the once common station robbery has become a rarity.
Yet, the merchant isn't running a charity. Many of the arrangements merchants have are sort of like the income tax - larger sales pay greater fees. This is the part where the merchant starts losing money on larger sales. This is the REAL reason most pumps limit sales to $50.
