Is a house connection room under the house useful?

How are these flexible pipes protected against frost? Or did you see something on TV about what they do in Georgia, but would never build that way in Wisconsin?

What you see on HGTV is not insulated

Permafrost soils are special. But you can see the stilts almost everywhere in the USA.

I once heard that protection against flooding and various animals was the reason for the stilts

More because it is cheap and fast. The wood is simply driven into the ground. Without protection and casing. That is why it rots away so quickly.

We talk about the USA as if it were a homogeneous country and laugh when an American cannot distinguish Holland from Belgium...

I am not currently informed. In New Mexico, I experienced several common types of houses, and in each of these types I lived for a while:
1. Adobe Brick - ecologically and energetically brilliant with enormous mass made of natural material. In summer, 45 degrees in the shade outside, inside pleasant, no air conditioning - in winter about 10 degrees cold, heating is hardly ever on, comfortable indoor temperature. Rarely with large windows. There's no variability through connections from below.
2. Wood frame construction on concrete slab - we know this too. Ours was majestic in size and delicate in wall thickness. Sound insulation through distance, I would say.
3. Wood frame construction on wood pedestal - very inexpensive and not planned for long service life. These were repeatedly torn down and rebuilt, reusing the pedestal whenever possible. Connections underneath can be easily laid. Saves costs even if after 25 years you throw the kids out and put something new on the pedestal.
4. Mobile home parks - here the connections are under an accessible pedestal. The houses are simply set on top and you can move with them. I often saw two semis as low loaders each carrying half a house. This flexibility makes special sense. I found that very "basic" and not far from camping.

A specific construction method was asked for here. Of course, there are many other and also advanced buildings. Every region is different as well. My good friend lives near Minneapolis and has a stone house. Is the absolute exotic. However, the house is (for American conditions) quite old.

I always find it funny when Europeans say "in America it is like this...", I couldn't resist. I was able to travel to nearly half of the US states. Enormous diversity (even in the variations of simplicity...).