Public transit in the US generally fails at the last mile for me especially in the suburbs. Self driving cars would be awesome for getting me to the train station. Currently I'd have to take a bus for that. However the bus stops at literally every block which is insane. Extremely frequent stops are a general problem I've had in both the bay area and the Portland area as well as the few times I've used public transit in LA. I'm more than happy to walk 5-10 minutes but I'm not happy to sit in a bus or train that is stopping all the time and never gets up to speed.