I did a few years in taxis but owning a car that is CC exempt is cheaper including parking in NCP holes. Part of the reason its cheaper is after some experience driving around the city, you realise that at least half the taxi drivers are taking the piss.
"the knowledge" is imminently replaceable by technology and is merely a party trick IMHO.
Once I had gotten a text from my wife as to where to meet her for dinner with friends. She didn't know the restaurant name, and had gotten the street name wrong. I just read the text to my London black cab driver, he asked me: "Did you mean XXX restaurant on [correct street name]?" (Note: there were multiple restaurants on the street). And sure enough, he was 100% correct.
That's the day I learned to really respect drivers with The Knowledge.
Conversely, got a taxi from Angel to Leyton and the idiot went via Poplar and the A13 and the journey cost me £55 for a £30 journey.
As you rightly point out, it doesn't mean that drivers won't still take the piss, but it definitely limits it. (Particularly when I compare it to virtually any other large city I've traveled to.)
There's an expectation that drivers keep their knowledge current. Certainly the examiners keep their knowledge current and test based on that.
Anyway, back on topic, "the knowledge" also covers alternative routes for road closures. I've usually been pretty impressed by black cabs. They know obscure little streets on the opposite side of town. Rarely have to give instructions. Compared to NYC where cabbies ask me how to get somewhere.
Yes of course!! Some other party tricks include reciting hours of lyric poetry from memory, adding large numbers in your head quickly, etc.
You're talking like the world is fair or something. There's not necessarily an equivalence between effort expended and value created.
This is really not the case with my London cab experience. These guys are super professional. In many other cities I've found cabs taking the scenic route but never with black cabs. I feel your 'half' claim extremely inflated off probably what was very few bad experiences.