Afterdark, you are quite correct. I sometimes arrange to be collected by hackney cab at Glasgow as it costs TWICE as much to get home in a licensed airport cab. The pre booked taxis, rather than pay £2.40 to await their fare either drive round the airport roads in circles until their fare spots them by the short stay car park, or they park illegally just outside the entrance of the car park blocking it. Both of these activities cause MORE congestion at the front of the terminal, exactly the opposite to what BAA claim the new collection procedure should achieve.
Why not have 30 mins free for everyone and make the whole business of using the airport more user friendly and pleasant. I think the traffic wardens and police would welcome this as they wouldn't have to move on so many vehicles from the airport roadways.