They do open it up to all drivers when it suits them. When I used to work for C2K I often worked right through a Saturday night/Sunday morning covering many airport jobs. It wasn't uncommon for a security man to approach me as I dropped at departures and ask me to pick up from the rank. Naturally I refused, pointing out that they chose to operate a closed shop and must therefore suffer the consequences. Unfortunately, there's plenty of half starved (immigrant) hungry cunts with zero self-respect who are happy to jump at their suggestion/command.