Your analogy is great except the OP didn't know about the racket. If I own a shop in NYC I will either know about the racket or it will be conveyed to me in some form. Extortion implies that the shakedown has occurred or the individual new and chose not to except the shakedown and paid for it with the lost luggage. The OP didn't know, hence no extortion or bribe. As to whether these people should be tipped, it is a long standing custom and their wages are based on the belief that they will receive tips. Not tipping them certainly affects their ability to live. While I feel for the OP, not knowing the tipping customs of a country you are visiting is certainly the OPs fault.