I don't think you analogy is quite accurate. The Airports "Own" the square footage in the terminal, and lease it to the airlines. The airlines are required by law to screen passengers, and most airports in the US use the TSA to accomplish that screening (the airlines charge $10 per ticket in a fee that is passed on to us the travelers), but it's still the airline's job. They (the airlines) set up the lines, hire the ID checkers, and handle the flow of Pax in airport so they are the ones controlling access. So, If I give the airline controlling access $50,000 per year in revenue and the average traveler is less than $500 I don't feel bad using the elite line