Where do you get that figure? Have you ever run a restaurant? Do you know what labor costs a restaurant? It averages 20%-30% of all costs. Increasing labor by 40% doesn't increase it's overall cost that much. Get real.
I didn’t say they COULD get the meal at half the cost. I said I suspected they would forgo the wait staff IF ... I repeat ... IF ... they could get it that cheaply.
My point, that you so obtusely chose to sidestep, is that the average diner is more concerned with cost than with interacting with waiters.