Premis of this movie. (Spoiler)
The whole reason for this movie is because Peter (Robert Downy Jr's character) puts his wallet in his luggage on the plane and then when kicked off he can't rent a car because surprise he doesn't have his luggage because it was on the plane.
Who does this!?! Everyone who has ever heard of air travel, so everyone has heard of luggage going missing. I can't imagine anyone like Peter would ever be so dumb as to not keep his wallet in his back or breast pocket. And because of this. He's stuck bumming a ride from Ethan and we have the movie.