OK well I guess the difference is we have no basements or crawl spaces here it's build on slab so no piping could be put in.
 
Just different I guess.

See the vents in my pictures here
 
Especially you can see them in the Kitchen ceiling.


 
- and the kids bathroom the last picture is a better close up.

Yeah--- I see them. We all have basements so I guess that does make a difference.

our downstairs stuff is in the floor - mostly, and our upstairs stuff is in the ceiling.
we do have crawl space down below, though...

when we lived in california, the house had all its vents in the ceiling or in the wall at the top of the room rather in the wall at the bottom of the room, but they were always always flush.

There really are no such things as radiators on the west coast (in the majority of houses, I know they exist, but not for most of the homes) and alot of the homes had baseboard heaters that extended but most people replace those for central air at some point.
Some of the older homes - built in the 80s I'd say have cadette heaters in each room on a wall by the light switches and while those protrude out from the wall a little, they're not really in a place that you have to 'decorate' around with furniture either

I was just shocked to see new construction with wall vents down low that stick out from the wall. That would have been something I would have expected to see from an older house where they were not quite 'up to speed' on the latest building techniques or on a house that was 'retrofitting' a forced air system into a house... but again, I am surprised to see it in new construction.

 
and to have it protrude from the wall? That just seems super odd to me for new construction

They're all like that around here.
 
Guess that's the style. I just always thought since warm air rises, it makes sense to have the vents on the floor. who knows? Either way-- this house is bizarre. It's the only one in its "development."