"Well, I mean...because you just got here recently. Didn't have a chance to learn the system, didn't spend the last eight years hearing people use terms like 'Circle toward Monument' until it made perfect sense to you."

Where the eight year olds at least saw their parents navigating the Tube for the eight years that they existed. He didn't mean to imply that she was less generally experienced than an eight year old, just that the terminology and mapping was likely different than the public transport where she was from.