[pandaman]

That's because few really like unbound density, people who move to cities want more density than a SFH-on-an-acre and/or perhaps can tolerate more of it but they do not enjoy density per se and don't "upgrade" by moving to even more crowded conditions just for the sake of having more nuisance.

Sure, many people would love to move to NYC, but how many people would chose to move to a tiny apartment over a giant penthouse in there, if given such a choice. Say the employer pays for housing with no cost to the individual and no limit, how many people would go for the smallest place in their preferred location and how many would go for the largest? If the former group is in minority this would explain how the cities, ruled by a democratic process, do not strive to pump density.