[richlevy]

Sounds like the lobster vs langostino issue. I guess the big difference is that if anything, prawns cost more than shrimp. Langostino are being substituted because they are a cheaper alternative.

Langostino is a Spanish word with different meanings in different areas. In the United States, it is commonly used in the restaurant trade to refer to the meat of the squat lobster, which is neither a true lobster nor a prawn. It is more closely related to porcelain crabs and hermit crabs.

In March 2006, Long John Silver's garnered controversy by offering buttered lobster bites advertising that they include "langostino lobster".[4] A Los Angeles Superior Court judge made no decisions in April 2006 on the matter when a class-action lawsuit was brought against Rubio's Restaurants, Inc., for selling "lobster burrito" and "lobster taco" that were in fact made with squat lobster.[1]