Yes, This is one of the most dubious Groupon "sells".

There are a very small class of businesses that excess capacity which costs nothing to use. These mostly the type of business where you're just consuming an "experience" - adult classes, skydiving school, etc. Unfortunately, a big part of business, classes, is already competing with the Internet. And so the rest is skydiving schools, martial arts schools, and yoga schools, the few places where you just have to be there. But those are pretty marginal.

Restaurants certainly aren't in that class. Food is expensive. Food is a significant share of cost for anything but the most expensive restaurants. Sure, restaurants may throw food away each day BUT the only way to profit from that optimizing that is to sell food cheap on the contingency that its available. That's far from the Groupon model and clearly would "cheapen" the feel of any given restaurant.

I heard of a restaurant in France years ago that priced by the hour. That could actually cut waste to nearly zero - but it would destroy "the feeling of specialness" which many higher end restaurants cultivate.