[jokteur]

You are underestimating how much trains and public transportation can do. Public transportation is abyssimal in the US, so I get why you think that it may not solve many problems.

If you take a look at Switzerland which did public transportation right, you will see that even in low densities areas, it is very much possible to get around by public transport. The canton of Graubünden (area: 7105.44 km2, density: 28/km2) has more train lines and bus lines than the city of Atlanta (area: 353.04 km2, density: 771.3/km2). Switzerland has a lot of tiny villages, evenly spread around. We don't have crazy dense cities, and certainly not large cities.

While public transport does not solve every trip and every commute, it is a solution for a significant percentage of the population. You can get to remote areas for hiking, leisure, ... You can find bus lines that connect one village of 30 people to another village of 100 people. They may not be frequent (4x a day), but they allow for tourist to go hike to remote areas, visit nice places, ... Also, public transit is clean here and very safe.

For some numbers: a decent amount of people commute by public transport (up to 50% in certain areas), and an even larger percentage of people use public transport for leisure activities (>70%).

In an ideal world, you would have decent public transit inside cities and around, pedestrian friendly cities, bike sharing, and fery vew (robo)taxis in dense areas. This makes the cities confortable to live in (less noise and polution). Also, intercity transit is very important (by train, highspeed train or plane). Then, in rural areas you would have robotaxis that can get you anywhere you want. The remaining vehicles on the road should be work related vehicles.