To push back a bit: SF proper must have the best bus system of any city in the US. It's possible to get pretty much anywhere in a reasonable amount of time, even late at night, with just a quick bus ride or two. I won't say MUNI is perfect but it's doing a lot of things right. Anyone who thinks BART is synonymous with SF's inner city transportation is really not making their way around the city by transit.
I don’t live in the US but have been to a few US cities for work. San Diego was horrendous without a car. DC was very good, even though when I travelled there had been heavy snow.
I’ve been to SF twice in the last three years. My impression of SF’s public transport (and to be honest, walking around parts of it too) was that I did not feel very safe using the MUNI buses, especially at night. I saw on the news that a British guy got stabbed near my hotel a week after I left the first time.
On one occasion I also witnessed a bus driver drive past a guy in a wheelchair in the middle of the day. Someone on the bus challenged them on that and I vividly remember that she said “I ain’t lettin no cripple pee pee all over my bus.”
The BART was much better but obviously is more limited in where it goes.
On the other hand, MUNI is incredibly overcrowded along certain lines now, and conditions on the buses are often filthy (though perhaps that's common in all dense large U.S. cities).
