Apart from the abysmal track record of the BAA, here are a number of reasons why it won't work.
-Demand at airports is not smooth. Imagine two 747 and one 380 arriving simultaneously. There is no way to get 1200 passengers smoothly into individual pods. And if you want them to use credit cards, walking out a fire door, getting arrested by airport police, 3 hours of interrogation and getting taken to your departure gate in handcuffs will get you on your next plane faster. For added hilarity, add a few wheelchairs to the mix.
-Ripple effects...if any of the pods breaks down, traffic stops. Even if they had the same MTBF as trains, the system will break 500 times more often. By the way, trains are a well understood technology after 150 years, this isn't.
-Goofing off. It doesn't have to be vandalism, but will the pods work with 25 college students packed into one?