They are faster. Taking the airport run lot option can mean a huge wait time. One trip I took I was stressing because I waited 20 minutes for the bus just to pick me up to go to the terminal and it was another 15 or so minutes of picking up more people . With fast park I am on the bus within 5 minutes (if that - I am usually on my way by the time I have pulled my luggage out of the trunk) and it doesn't take much longer than that to leave the lot for the terminal. It is also faster getting back to my car on return.