I remain unconvinced that it's crazy. I've been driven in London by a cabbie when there are unexpected road closures and diversions, and there is absolutely no doubt that he did better than any existing system at getting me where I wanted to go efficiently despite the problems.
GPS and SatNav is currently no solution for the streets of London. Remember, it's been there a long time, and initially grew without the existence of cars.
I've been driven by cab in London to an address we later found was on the same physical street, it just changed name halfway. The folks at the destination laughed and said that while the cabbie should have just driven straight down the street, his actual route took us about four times the distance it should have...
It seems that The Knowledge isn't necessarily implemented for The Punters :)
There's knowing the quickest route to take and then there's taking the longest route you can get away with. Two different problems with the same data set.
GPS and SatNav is currently no solution for the streets of London. Remember, it's been there a long time, and initially grew without the existence of cars.