Aren't London commute hour trains just as crowded as those in the US? Whether the train shows up and departs on time, or goes where you want it to, is rarely the problem for existing systems in major US cities. It's about the experience of being inside the train for an extended period of time.

I'm about to double my rent and halve my square footage to get away from BART. It has noting to do with reliability and everything to do with standing on a crowded moving vehicle for 90 minutes a day.

Modern cars are palatial. Even the best (fast, frequent, good coverage, reliable) train systems are squalid and cramped when they are needed most.