The problem is utilization: you can't get 9000 persons per hour via busing in most places, weighting by area. Fixed routing scales poorly compared to cars (or bikes which have their own drawbacks) trying to match many-to-many riders-to-destinations.
What's "most places?" This is a traffic flow that's achieved routinely in about every medium size european city. And the way population is distributed, most people live in comparatively dense population centers, across the world.
A medium US city has the commute time of 15 minutes. It's unachievable with transit in any scenario.
> And the way population is distributed, most people live in comparatively dense population centers, across the world.
Yeah. And it sucks. The distributed nature of the US cities gave people far more economic opportunities than in Europe. This resulted in faster economic growth (and still does).