Comment by standardUser

Much of the US was built in ways that make mass transit impractical and inefficient, but those same areas have comprehensive road systems already built out, sometimes excessively. That gives self-driving taxis an opportunity to fill in the transit gap in the huge expanses of this country ill-suited for trains and buses, but well-equipped with roads.

I think the actual concern is around medium-to-large cities and metros, where self-driving cars will compete directly with mass transit, much like Uber does, but potentially much more competitively.