It was one of the Doctor’s favourite details about the universe outside Gallifrey, as well as one of the things he found most confusing. Time travel was, to Time Lords, about as exciting as the postal service. It was mostly cheap, mostly reliable, and everyone used it. Yes, sometimes it took an awfully long time to get to the desired destination, and sometimes things went spectacularly wrong but, all in all, it was just a thing that happened, and you were a bit weird if you talked about it too much, particularly at parties. Non-Gallifreyans, however, genuinely believed time travel was magic, while ignoring the far more impressive inventions of their own cultures. Such as, for example, a delivery system where one paid a pound to have a folded piece of paper inside another folded piece of paper taken from Bingley to Guam.