if you want everyone to use mass transit

That's the point, nobody wants to move people in the middle of nowhere to buses. Everyone wants these people to move to buses:

That's like a half-full train's worth of people if they single-seat, which they do, or 5-10 buses.

Imagine how cooler the place would be if that 16 lane road would be a 2 lane train track.

Eh there are plenty of places that have less population density than the US but they do just fine with transit. It might be true that most US cities are poorly designed for transit, but the density isn’t a the reason.

Someone has to see Not Just Bikes. Capitalism was the driver to the sub-urbanization process made after WW2 in the US, as a national economic policy to orient growth around building detached houses, private cars and suburban infrastructure (and secondary security considerations of reducing losses and damage in case of nuclear bombs in cities). The US was not a ''very spread out' place before WW2 (i.e. for the vast majority of its history), in fact cities like San Francisco were world leaders in mass transit, and trains were the axis of transportation of both people and goods (even existing suburbs were connected to trains, in whatever shape and size they come). The us cities spent and spend an enormous amount of money and debt to pay for all the road infrastructure, that even neoliberals say it's not economically sustainable, and that money can also be better used paying for higher quality mass transit, not the tertiary thought they give it now (horrible buses that stay in traffic with the cars for the poor people that can not afford a car). Most people do not work remote all the time, even flexible / hybrid workers need to transport themselves some trips per week. Not to mention that full remote work may over time trickle to foreign countries that do the service cheaper, and the work remaining onshore is work that the owners need-want at least hybrid or on site workers.