I believe those terms got banned in one of the financial reform bills of the past two years. They're not allowed to prohibit discounts for other payment forms anymore.
Perhaps it's this one:
> (a) With respect to credit card which may be used for extensions of credit in sales transactions in which the seller is a person other than the card issuer, the card issuer may not, by contract or otherwise, prohibit any such seller from offering a discount to a cardholder to induce the cardholder to pay by cash, check, or similar means rather than use a credit card.
Looking at Visa's current terms, they don't seem to run afoul of those regulations - but Verizon is still violating them. Visa says you're allowed to offer a discount to non-credit-card payments, but it has to be presented to the customer as a discount for cash/gift card/e-check/whatever payment, rather than as a surcharge for paying with your credit card.
If that is the case then this change would have to be a 2 dollar increase to all bills and then removed if you pay not using a CC. In which case this would be a material change to the contract.
From the article: "Customers can still enroll in a service that will debit their bank accounts or charge their credit cards on a recurring basis for free."
What would happen if Visa or Mastercard said "you're in violation of our terms, we're cancelling your merchant account"?