Having invested many hours into gaining my understanding of how it came about, around the early 1990s, folks here were having difficulty getting condominiums financed at rates and terms they liked. Along came some "crafty" attorneys to rectify the situation. They created the "townhome" by simply adding the description of the unit as being the unit "and the land under the unit" (which is never identified except by the exterior of an existing structure) plus the typical portion of the common elements. Somehow, this passed muster, and these townhomes were financed with rates and terms typically enjoyed for traditional SFR on a deeded site. For most of 25 years, there were probably as many of these created as there were condos, maybe more. The only problem was, the word townhouse or townhome didn't exist in state statute. It became a problem and was batted about during every legislative session for 15 years or so until the definition of townhome was added to the statute. Last I spoke with the attorney who provided most of that history to me, there as yet to be litigation, and thus precedent, regarding the exact status of those units that were created when the entity didn't exist.
I find it rather underhanded that it got off the ground, but at some point, it had to be resolved. So now, some must comply with subdivision laws while others can subdivide by including a sentence in a document without cost.