You are not right. The crime being committed is fraud and the guilty party is the restaurant. If they refuse payment for the actual payment, that is their problem. Any court in any jurisdiction in the world will side with the customer in a case such as OPs.
Why would the card company take on the dispute? If you signed or entered your PIN have you not agreed to pay the amount shown for the thing you received?
Why hasn't anyone court in any jurisdiction found this by now then? Added fees are pernicious and annoying but I'm not aware of them being found to be illegal. The most likely end result is the court finds your lawsuit is frivolous and simply dismisses it then you end up paying the $8 charge if you are unlucky legal fees for bringing a frivolous suit.
Instead of relying on your fictional understanding of how the law works in every state of the union the more logical thing would be to either vote with your wallet or work to pass local laws against such fees or hell why not both.
>The most likely end result is the court finds your lawsuit is frivolous and simply dismisses it
You're completely right, the case will get thrown out. If you remember, in your scenario it is the restaurant suing the customer for not paying the 20% fraudulent fee, it's not the customer suing the restaurant.
Trying to add a fee after the price has been agreed and the food consumed is plain fraud. That's why they won't take you to court. If you dispute it while in the restaurant, they will let it go. Because they know the justice system will side with the customer.
Imagine for example if Ticket Master would charge extra fees after a concert, preventing you to leave if you do not pay. Not even they would do such a thing.
