ADUs seem like a bandaid solution for lack of housing supply in desirable areas. Not that I think they shouldn't be legal, but we're talking about paying hundreds of thousands of dollars for what amounts to a shed in someone else's backyard just because you want to live in Seattle, SF, etc. It's so bizarre, and if this solution is taken to its logical end, you literally have cities full of single-family homes with a…
We already have townhouses (that share a wall but own their own land) and condos (which share land and the building). There are also well-established legal precedents for things like easements (e.g., for access, water, sewer, see [1]). I'm not saying this is a good idea, but is it really that different? [1]: https://en.wikipedia.org/wiki/Easement
In Seattle, ADU/DADU are built in Single Family House zone, you can tear down a single family house, build 1 main + 1 ADU + 1 DADU which is total of 3 without zoning change, then you can sell all 3 of them as Condos, require buyers share something like water bill.
Townhouse has to be build on the areas that are up zoned by the city.