Name of town= Dover, VT

Two things you get wrong:
* Zoning - it takes a 2/3 vote to change zoning; the laws are FAR more popular than you think. There is a movement in my state (Mass) to reduce that to 50% to take advantage of your bandwagon.

* Greed: NO, it's the exact opposite. If I could get a variance, I could put a 2nd apt addition on my house and build a duplex in the front yard, and walk away with $millions for those 4 units (nevermind that I'd just trashed the protected wetlands that make up 2/3 of my yard, and the neighborhood). Every one of my neighbors in the whole town could do the same or better. But no one wants to, because we came for the quiet, the trails, the wildlife. It is the opposite of greed.

* There are plenty of neighborhoods with very high population density and low cost housing within 5 miles of this 2ac-zoned town. But "nobody" wants to go there, because, well, the same reason I don't, dense-pack, pavement, noise, traffic, crime, no room to park+++, and plenty of housing IS being built there (a new 200+units 3.5mi away)

Simply trashing the low-density areas that literally generations have invested in building is not a solution.

I hear you like the Japanese model a lot, but I do not know enough about it to have an informed opinion. I do know that Japan is a very different society than ours, demographically, and culturally. You speak of "individual property rights", but I think that you would find that Japan constrains those much more tightly than in the US.

To your specific question about Grandma Apt, Duplex/Triplex/Quad:

A Grandma suite is typically allowed in these zoned towns with a variance, and sometimes restricted to bona-fide family members (not AirB&B suites). The Duplex/Triplex/Quad is specifically not allowed, BECAUSE HAS MASSIVE MEASURABLE DELETERIOUS EFFECTS on services burden, nuisance and safety. Every single issue changes: traffic, burden on school districts, water/sewer, road maintenance, crime.

Of course, a single instance of a single duplex/triple/quad has a negligable effect, just like a single noisy, polluting factory. But, systemically change the rules so that those are everywhere, and everything changes.

Taking one of the most bucolic 25 SqMi, towns with 8.5K people at 350/SqMi, and changing it to quads makes it a lot closer to 40K ppl, 1700/SqMi. Right now, everyone has an individual well and septic system. With that population, the wells and septic would fail and we'd require an entirely new centralized water & sewer system at a cost of $100s of millions. We already have one tiny such development, and it already has caused well failure for itself and the neighboring wells, requiring a expensive mitigation measures, digging temp hookups to adjacent town systems, etc.

So, if you want to show up with several hundred million dollars to build out all that infrastructure, support 5X larger schools, 5X larger fire & police, road maintenance & buildout, and so forth, then maybe that makes sense. But don't act like "oh, just change the zoning because none of it matters" is an actual argument, because with that argument, you show that you literally do not know what you are talking about. Ignoring collateral effects does not make them disappear. Similarly, ignoring that it is 67% vote and not 51%, does not make you look knowlegable.

And you talk about can't afford it in the city, and long commutes. Well, if that's the problem, you need to focus on higher density taller city buildings, and not on changing zoning in the places that geographically require long commutes. I can get on board with that.

I think there is a real case in the cities for taller and higher efficiency apartments, like the tiny house movement, where it is fewer square feet, but just packed with fold-out storage and conveniences. I don't see how allowing such smaller units would change much about the city, BUT I know that I don't know enough about the topic to say (I've liven on Manhattan in a small apt, could have lived OK in a more efficient such unit, but I don't know enough abt the real situation there to want to impose such a rule change on them).