All of these techniques come down to the fundamental implication of scarcity. Specifically, limited-quantity scarcity.
Parker & Lehmann (2011) investigated the use of scarcity within a supermarket store. Participants were required to select the items they wanted from options available within the simulated store and subsequently explain their choices. They found that people chose the more scarce items. The graph below demonstrates that the relative scarcity level impacts choice, however, the type of wine did not.
Cialdini, R. B. (1993). Inﬂuence: The psychology of persuasion. New York: Morrow.
Parker, J. R., & Lehmann, D. R. (2011). When shelf-based scarcity impacts consumer preferences. Journal of Retailing, 87(2), 142-155.