Second clue is it is made from concrete. Concrete by itself is not water tight. It can be made water tight but some significant effort is required. Just ask anyone who has ever built a basement.
There haven't been any problems so far, but I live in Seattle which doesn't actually rain that much (in terms of inches per year - 38 average vs 47 for New York) despite its reputation. It's gloomy and drizzles a lot, so that's probably where the reputation comes from, but it rarely really rains like the kind of rain you'd get in a Houston rainstorm.
The trouble is leaves, and when it snows a foot or two, the slush clogs any attempt at drainage.
Putting 1/4" steel mesh over the grate will at least make the leaf clogs visible so you can clean it.
When it snows heavily, you'll need to proactively shovel the drain clear, and clear the snow between the garage door and the drain.
I'm not sure if it is just purely stylistic or if they were more trouble than they were worth so builders stopped digging them in.
When we were looking at houses, we couldn't really stand most of the older ones because the basements were so dreary. There was just nothing to do with them, yet they were counted in so much of the home's square footage.
Lots of homes in my area are constructed on inclines with houses on one side rising from the street and the other side declining from the street. With some basic civil engineering principles (water flows downhill) we don’t see any issues with water in basements or garages, etc.
It was sold on a massive loss (around 150k to build years earlier). There must be something terribly wrong judging by the price alone.
The people/company selling it might have had other monetary problems and were thus selling because they needed money and couldn't afford to wait.
If you build an underground house it is probably because you want an underground house, if you then die your heirs might not want an underground house, but to sell it they have to find someone who wants an underground house, thus to make it more interesting to buy they lower the price because maybe someone on the fence about living in an underground house will be willing to give it a try.
For a modern presentation, see https://topex.ucsd.edu/geodynamics/HW3_2010_presentations/C_...
Autographic notes might be found in the vicinity of https://gallica.bnf.fr/ark:/12148/btv1b9061905f/f9.image.r=f...
The closest to a cellar discussion I find in his 1822 book is: https://gallica.bnf.fr/ark:/12148/bpt6k1045508v/f43.item but in this book I only find him working out the zero variation depth, not the depth for six-month temperature lag. Anyone have a title for the cellar paper? (just before giving up I found Mémoire sur la température du globe terrestre et des espaces planétaires, which mentions that one would need a good sampling of local reflectivity and plenty of computation to derive global heating due to insolation.)
related: https://en.wikipedia.org/wiki/Age_of_Earth#Radiometric_datin...
An underground home needs substantial strength to resist the weight of the soil all around it. Concrete is strong and cheap but porus --- not watertight. To make it water tight, you need a sealed membrane that extends all the way under the foundation. Otherwise, water/moisture will be seep up through the floor. Saturated soil surrounding your home will exhibit water pressure from gravity trying to force it into your home. The required moisture membrane is subject to being broken during construction or afterwards from settlement.
Personally, if I was sold on the concept, I would look at the possibility of building up --- not down. Think of a tube open on the ends or a box open on one side but otherwise covered by a mound of soil. The foundation could rest on one big French drain system and this could be extended up the sides as well. This way, the force of gravity can pull water away from the home, not into it.
If you want a waterproof container I'd look into used plastic or fiberglass industrial process tanks (preferably ones that held something not too nasty, so likely from the food industry), dig a hole, do proper compaction and gravel base then plop the tanks in (fill them with water or something so they don't float away) and then pour concrete around them for strength (leaving holes for your vents and doors and whatnot). You're going to have to become well versed in chemistry and construction to prevent all your "rooms" from leaking at the doorways where you have cut holes to join them together.
Checking google maps, it appears that they've finally remediated these structures, but they were in fine condition up until then.
Their property is on a what looks to me to be quite a steep hill. I.e. the steps lead down to the front door, then there's their living space, then their deck is on supports above the slope.
I know nothing about water levels etc. in buildings. Is this still as much as problem (since it's only a "catch basin" from the one side of the slope)?