I see so the primarily utility of Groupon is that businesses can pay for a chance of repeat customers and/or extra spenders? I think the theater is a good example of the latter.
Then the question arises, why can't businesses do this themeselves? Why can't the breakfast place you frequent just advertise $20 worth of food for $10? Why Groupon? Is it because Groupon can send foot traffic on demand for a cut of the sales?
For instance one breakfast place we frequent is always running a $20 worth of food for $10. We always end up spending more. Besides soft drinks have ridiculous margins. Movie theaters make most of their money from concessions, food (movie and dinner type theaters) and the bar.