There's nothing exclusive about the two. Good systems should be self-justifying. But if you want decent travel times the current BART can't provide them. You'd

There's nothing exclusive about the two. Good systems should be self-justifying. But if you want decent travel times the current BART can't provide them. You'd need something like Personal Rapid Transit to get good trip times at the intra-urban scale. But the same argument you are making here - envy of something that doesn't even exist - is why we keep getting the same transit systems that are hard to grow because they don't provide enough benefit to enough people.