The technique is a duplication of forest growing trees that are elongated due to a limitation of light in competition. Most are second story or middle canopy trees of various species.
Essentially a tree is grown as a multi-trunk specimen, and if the original is a single stem tree then the trunk is cut off so that multiple trunks emerge that when combined amount to the girth of the old single trunk. These multiple trunks are then reduced to 2, 3 or 5 trunks.
Next the sun deprived or shade loving specimen is studied for the pattern that emerges when there is high light competition and high root density. The lower branches are removed in patterns that are probably more readily seen in ikebana. Meaning that if I wished to see a minimalistic pattern that has aesthetic value then it is easier to study ikebana if one does not have a dense forest of examples close at hand.
for the most part, as the examples you have shown are maples, the pruning techniques would be for maples. However, these could as easily be (in my area) Alders, Birch, Hawthorn, Oak, (etc) that are pruned in a maple manner (technique) wherein the emphasis is on the canopy rather than the lower and mid-branching.
Mathematically if this is easier, there is a single large trunk, replaced by many small trunks. The density of leaves is the same, and reduced by removing the inner branches in a seemingly random pattern..
and when the neighbouring trees canopies encroach on the other canopies the trunk numbers are further reduced, so that the tree is thinned (weakened), the root masses also encroach on each other creating a limited space for roots. With a finite root system the tree needs to be maintained with a lesser number of trunks and related leaves over a wider area of canopy.
simply put: less roots = less possible leaves -- until a balance is created between the competitors that fulfills your aesthetic.
This gives a sense of deep forest and dappled sunlight, that also reduces the amount of maintenance work to be done.
I am not overly familiar with plants in SoCal and would suggest others closer to the area answer your species question.
(how do you come to appreciate this aesthetic? Or why do you wish it? need it? (please explain) It is quite advanced in garden aesthetic timelines (hm, wrong words perhaps, however nothing better comes to mind) edzard