>In the context of the cost of a building, the cost of these elements is near-insignificant.
The same could be said of 99% of building code requirements...and it adds up.
Houses in Europe have such building code requirements and yet don't seem outrageously expensive by any means.
Shock! It turns out that doing it right at scale just isn't much harder, and pays society back in spades over the life of the building.
IIRC there is a limiting factor with (ground-based) heat-pumps, though... the in-earth elements can't be placed too close to each other before they lose efficiency badly through competition for the same heat energy stocks. (Somebody who knows more about this should correct me.)