The point I'm trying to make is that public transit can be made much better and more enjoyable. Instead of saying "well, it sucks now" we should say "it sucks now, let's make it better". The budgets currently devoted to maintaining roads, traffic police, etc. could be used to improve public transit instead. Motorized walkways could double or triple your walking speed (something you say you already do) in lots of places.
I grew up in Kharkiv, Ukraine, a city with roughly 1m people and several public transit options: subway, tram/light rail, commuter rail, taxis, and buses. While some of these got to be somewhat gross, the subway specifically was always great: always clean, always air conditioned, marble floors and walls. By contrast, Boston's T/subway/metro is always looking like there is either construction or rodent extermination going on, and it is incredibly hot at all times. It's also incredibly noisy because of the wrong size chassis on some of the train. I believe that if a country like Ukraine can have nice public transit, the US should be able to figure it out too.
It takes over an hour to get from most places to downtown.
It’s getting from one residential neighborhood to another that’s really annoying. I have students scheduling over an hour to get to high school, because SFUSD has a policy of promoting school integration and doesn’t provide buses. Teenagers getting enough sleep? What a silly idea.
I haven't spent much time in Boston, but public transportation in SF is a joke. Average fleet speed is 8.1mph, the slowest in north america. Even express lines are outpaced by bicycles. Heck, I've been able to outrun the N from Civic Center to Ocean Beach.
In addition to being slow, SF's public transport is disgusting. Many homeless leave filth on busses and trains. I can't remember a time I've taken Muni or BART and not smelled urine (or worse).
Then there are the constant annoyances stemming from the public part of public transportation: being packed into cars like cattle, sick people spreading germs, passengers playing music out of their phones, etc.
All of these problems combine to make a distinctly unpleasant experience. That's why I often Uber or just walk in SF.