> American cities have largely failed at making bus rapid transit economically sustainable and comfortable for the broader population

I don't know that's true at all. Buses generally work well wherever I take them, and they are widely used in cities around the country. In many cities I can just walk to the nearest corner, or maybe another block, and catch a bus whichever way I'm going. I often don't even need to know the routes.

IME a certain socioeconomic class is unfamiliar with using them, with how to use them (a barrier to adoption), and with sharing public transit with others (I don't know about you). Didn't some SV billionaire (Zuckerberg? Musk?) once say something about people should be afraid of psychopaths on public transit? Many disparage any public service, automatically assuming they are incompetent or substandard.

> Privately-operated buses on city bus lanes seems fine?

Public transit needs a network effect: When more people use it, there are more buses and trains and they come more often.