Unless they inform me of this prior to ordering they had better take it off my bill.
And if they inform me of it prior to ordering I will go elsewhere.
There is no law that requires me to pay this surcharge.
Of course there isn't, so you think you're not paying it. There is a law that makes the restaurant pay the surcharge. Any money a restaurant has comes from you - the paying customer.
So if they don't add a surcharge, but raise the prices instead to cover the costs, you'll still pay more, but then you'll be happy? Because why?