Earlier quoted context omitted.
I've seen and heard of this in Mexico and Latin America as well. A lot of US housing styles, such as saltbox and narrow townhouses, are also attempts to game older versions of the tax code
At least in recent Mexico it's not because of taxes. People don't have enough money to finish it and they leave it for later which usually never happens. Also they leave the possibility that next generation can add a new floor.
Especially the never happens part.