I had it happen to me a few times that my credit card was blocked or deactivated by the bank without letting me know, and I only that found out while trying to pay. To counter that I always carry some cash. Now I've been hearing about some newfangled "cashless" restaurants. Thankfully, I'm not aware of any where I live, but what would happen if I went into one of those, ate, tried to pay with card, it failed, then I offered to pay with cash?
As I understand the legality would work something like this:
I accept the the contract where I agree to pay with card in exchange for food
I attempt to fulfill the contract to the best of my ability, but am prevented from doing so by circumstances beyond my control
At this point I owe the restaurant the money, but since the original transaction failed, this is a debt, which I offer to settle with legal tender
Is that how it would work? Or are there some additional issues? Or is it one of those gray areas that'll only become concrete once it happens and actually goes to court?