While I understand how you can understand that from my post, the stream-of-consciousness style of posting on websites muddled my points:
- I see as the only long-term sustainable trend for much more people to move into smaller, much more densely populated areas - megacities. But there are no (not yet) facts that corroborate this claim, although more people in my field and adjacent fields are at least informally starting to share this idea. Not that it's very relevant what the objective situation is - many people feel cities are Bad and think we need to move away from them. And politics follows popular opinion, on macro topics like this.
- 'Accessibility' is not just 'smaller centres'. Without wanting to get into the debate over which of the 5000 definitions is the 'right' one, what I meant was that thinking of time it takes to get to different places in terms of 'we need to increase rush hour capacity so that I can get to work faster' is (apologies to the GP, not meant personally) stupid. The congestion-decreasing effect of adding a lane on a main artery lasts, give or take a few years, 5 years. After that, people have adapted to the new circumstances - i.e. bought houses further away from where they work, because it's cheaper there (in the first years after the intervention) and thereby made the problem worse.
- I disagree with your assertion that the trend to build more and wider roads and more public transport are a way to deal with concentration of economic activity on less area. Moving people into dense centres is, but 'improving transport' is (imo) a band aid to deal with negative externalities of densification - i.e. rising house prices, lagged upgrades of amenities in areas that increase in density, etc. Said in a less roundabout, academic and cautious way: politician build more roads to deal with constituents bitching about not being able to buy a detached house with 10 ares of lawn for their children to play on in the area where I work, and look there are plenty of houses in that shithole farm town over there, just build a road and I'll vote for you.
I'm not quite sure any more where exactly I'm going with this to be honest, just wanted to say that the solution to transportation issues is not 'build more roads' but 'create an environment in which people will naturally need to travel less'. But building roads is easier, of course.