I agree. In the US trains and buses deliver slow, unreliable, inflexible, expensive, dirty, and dangerous service at high cost.
It will be great to see the safe, clean, flexible, and affordable transportation that will be possible with self-driving cars.
Cars are noisy, take a lot of space, are crazy expensive, dirty (even electric ones leave tire particles in the air) and are involved in 99% of road incidents. Them being self-driving wouldn't fix any of these issues. Maybe they'd be a little safer? But even that is doubtful.
I understand US transportation is in a dire state right now. This shouldn't be a reason to make it worse, quite the contrary IMHO.