Wait, they're proposing four story, wooden multiple-occupancy buildings? Would those meet fire safety standards anywhere in the developed world? I doubt their example photo (sheltered accommodation for the elderly in the UK) is wood, since we don't generally build that way, and from what I can tell it cost substantially more than their budget despite being built somewhere with low land costs.

I also notice that their photos of how six-story buildings would look are actually mostly four stories or less - and even at that height, they're starting to look pretty crowded in and dark. That's the trouble with dense high-rise buildings - you rapidly run out of light and privacy. This has two nasty effects on their proposals: it limits the density at which you can manage to cram them in and puts a lower cap on the minimum size.