from the factory built townhse mods i've seen, you wouldn't be able to know it's one, only if you did see the layout of the basement joists. seems in a more suburban/rural area it would be easier with a mod built home than finding a general contractor to build from scratch and price of getting those construction supplies to the site, and time frame..
my issue is that are there any kind of comps to do an appraisal with some new construction.
but hey, i'm privileged big city little row home appraiser.