There keep being more people and those people keep wanting to live in the same places.
But, the people already in those places don't want them - charitably, because it gets too crowded. Turns LA or SF into Manhattan, where you pay a lot for a mediocre shoebox.
Better transportation gets us a ways - when you ask someone in LA how far away something is, they tell it to you in time, because that's what matters - not the physical distance, but the temporal one. Better transportation means more physical space is accessible within the same "city".
But, it strikes me that this is nearly the same problem as corporatism and monopolies - as power concentrates, power concentrates faster. I guess that extends past money and politics to society and populations.
So if the government needs to redistribute power - wealth (universal basic income), politics (democracy vs autocracy), access (mass transit, education)... does it need to build more cities? Not build existing cities larger, mind you - but cause more cities?
The west coast grew later than the east coast. We have, what, three major cities / metropolitan areas? San Francisco, Los Angeles, Seattle? Five if you move the bar to include Portland and San Diego? East coast has more than a dozen MAJOR metropolitan areas, and how many more when you move the bar?
Maybe the answer isn't higher density housing in the cities we have where everyone wants to live. Maybe the answer is getting more cities where everyone wants to live.
Sure, it's not exactly like New York has a monopoly on metropolitan-ness, and we need to go all anti-trust on it... But you get the idea, yeah?
Make me think of Dublin. What was Dublin two decades ago? What is it now?
Makes me think of - what was it called, where you make a city with different laws, one part test bed, one part diversity? Happened in the Renaissance, and it's what Hong Kong is.