Shouldn't a prototype city of the future be built around walking and public transit with cars being more of an afterthought?
You see a lot more cars in the outskirts and in smaller cities (like Kyoto) where they haven't hit critical mass, or there has been mismanagement of the transit infrastructure.
What version of Tokyo have you been to? Cars are everywhere in Tokyo. A quarter of commuters drive alone.
That's really low compared to NA where even in a metro area I'd guess it's at least 50%.
Your point was that "cars are almost non-existent in Tokyo and Osaka", which hardly is supported by the fact that 25% of commuters drive.
For example, I live in Seattle, city with one of the worse traffic situations in the country. However, if you stroll on most of the surface streets in downtown, you'll never notice that. Most congestion in the metro occurs on the major freeways that allow one to travel through the area on a north-south axis: SR-99, I-5 and I-405, and on the surface streets and ramps directly leading to these freeways. Before you get to these, and after you get off them, you'll see rather little traffic, and pretty much no congestion to speak of.
What I find interesting is there wasn't really any illustrations of the reported three layer road system, and the majority of the illustrations are of huge, open walkable areas. I would love to see how they're looking to address separating slow speed traffic from high speed traffic while keeping them both useful.
In fact, a lot of science fiction I can think of describe Disney-style people mover things that quickly and efficiently take you exactly where you want to go. I guess they aren't exactly cars, but they aren't exactly trains either.
There, residential zoning is mixed with business zoning. There is no such thing as a "suburb", because you have apartments nestled right next to grocery stores, cafes, and restaurants. I don't think I ever had to walk more than 2-5 minutes to get to a convenience store. Cars still existed of course, but so many people walked, rode bikes, or took public transit. (It helps that both countries have extremely good public transit systems).
Once I realized how nice life could be, I started hating suburbs. I hate having to drive 10-20+ minutes just to get food or groceries because the only thing around you is a vast sea of houses. I hate that public transit is basically nonexistent, or if it does exist, it's slow and not on time. I hate having to drive, which is both unsafe and prohibits me from studying or getting work done, because I have to pay attention to the road.
Centering around a suburb model is one of the US's greatest structural failures.
Regardless of gas or electric, cars are dangerous and kill more citizens than just about anything in modern society. Furthermore, encouraging people to drive everywhere rather than walking or cycling only exacerbates the obesity crisis (another major driver of mortality).
A lot of that science fiction was written by Americans.
Their overuse, rather, is bad.
That is still a tremendous improvement over having to drive everywhere. The quality of life is so much better, it's almost indescribable.