Open a route in downtown San Francisco and drag the destination around. Watch how convoluted even simple routes get. Destinations half a block apart need entirely different routes.
When I moved to San Francisco, getting into my car often triggered Pavlovian fury for the impending battle with one-ways, no-left-turns, you-screwed-up-now-go-back-and-try-agains. Now rage has gradually simmered down into a cautious wariness, an ambient “what are you going to throw at me now, city?” I know to plan my routes. I know the three places where you can turn left on Market, and I know not to try turning left on 6th. I am no longer a newcomer.
Driving in San Francisco is complex because it isn't geared for newcomers. When habitual users have more pull than newcomers, dramatic changes become hard. Adjustment would be needed. Old habits would have to be broken, replaced with new ones. Much easier if you're a veteran to just apply the duct tape of a new exception. And the exceptions gradually pile up until you're oblivious to even the need for a ‘last left off Market’ sign.
My lesson from all this: If you have an audience, listen for signs that you're ‘inaccessible to newcomers’—it's keeping you from moving to a larger audience. ‘Inaccessible to newcomers’ is a sign of complacency, an opportunity for an upstart to disrupt life as usual for the incumbent.
But there's no opportunity in San Francisco. The last thing a city needs is more drivers.