Did you know that many airlines now tack on thirty to forty minutes to their flight time estimates? Their statistics of on time take-offs and arrivals were getting so bad that they decided to covertly lower our expectations by telling us the flights would be longer than they actually need to be. So, if you pull away from the gate and end up taxiing on the runway for a half an hour and are still, somehow, miraculously on time, it is not because they made up the time in the air. It is because they kind-of, sort-of didn't exactly tell the truth to begin with.
It's still faster than taking the train or the bus, naturally, but there's something about slipping that in without simply telling their customers they were doing it or why that smacks of the old corporate secret-world-domination agenda.