'The Knowledge' certainly eliminates the dim-witted or even average, at the outset - even if it inflates the egos of those who have truly mastered the City. I'd agree that we lesser mortals would appreciate the assist from some transistors, especially within such an ancient complexity. But as you note, the instant go-arounds would occcur only to those who have somehow stored All That info. Somehow..

Loved every taxi ride / just to observe a virtuoso in his Element {no hers then, as I recall?}

And as one who once had to navigate, in a borrowed car, from Stoke Newington to some suburb, late in the evening to return a er, bird to her nest (and navigate back) -- I can attest to the Confusion-factor as the "High Street", while curving all about.. changes-Names! 5x or so ... all, while you keep scanning for an expected next turn. And remember KEEP LEFT, Idiot! as your constant mantra

KEEP LEFT, Idiot! ... KEEP LEFT, Idiot! ... KEEP LEFT, Idiot!

Dunno how you'd Do That with heavy traffic too. Or look at your cute color map every 15 seconds. Take a Taxi and Live, I say.