Doesn't need to be easy for any particular condo -- just needs to be more appealing to own (in) a 4-plex with a yard than a larger faceless tower? You can't ex

Doesn't need to be easy for any particular condo -- just needs to be more appealing to own (in) a 4-plex with a yard than a larger faceless tower? You can't exactly force people to sell SFHs either, but that doesn't stop developers from finding a few adjacent parcels to join together. (Rather, it's not the difficulty that stops them, it's typically zoning.)