"by American standards" is doing a lot of lifting. On a scale of 1 to 10 I'd give SF about a 4 compared to cities like Tokyo, Paris, Berlin, London, Amsterdam, Seoul, Singapore, ...
Caltrain is no slouch - punctual, clean, safe, really good wifi, electric.
I don’t understand the boosters saying BART and Caltrain are good systems. When I lived there, and part of the reason I left, those systems were frequently delayed, full of drug addicts, and they lacked comprehensive service throughout SF, requiring dependence on Muni, which is worse than the other 2. I don’t think those who say this is a great system have been exposed to how other places in the world handle these things.