Clever - win / win idea. Allows business to discount when they have excess capacity for services (so it doesnt go unused... so they make a new loyal customer) and allows the consumer to get a deal and try something new.
It works! (Segway tour for 2 for $19. Four horseback riding lessons for $60.)
Legit merchants that have confidence in the value of what they are doing... cut their profit because they are optimistic you will like and be back!