>>21438877 (OP)>Is making large reservations at a restaurant, then just not showing up totally unethical?It's not a victimless crime. They probably have a whole section being held empty, and it'd affect at least 1 waiter.
As soon as you know you will have to cancel, you give them the courtesy of knowing that. That would be the polite thing to do. If you used opentable, it's a simple click and confirm to remove or alter a reservation. A phone call is nice too.
It's groups like you who create those annoying restaurants that now need a service fee to secure reservations along with your credit card numbers. Some of them even have cancellation penalties.