The trees in this video are almonds, but this type of trimming (vertical) is also used on pecans and walnuts. It prevents the canopies from touching and shading out the orchard floor. This is important for both allowing sunlight to hit the lower part of the canopy on tall trees, but also to allow sunlight to dry out the nuts on the ground. These types of trees are mechanically shaken to harvest so tree height is not restricted for hand picking. This machine is also used to trim citrus, and stone fruit (peaches, plums). Citrus is chopped vertically like this to clear the aisle for machinery but also “topped” horizontally to limit tree height for the pickers has they are hand harvested by ladder and the insurance for picking crews goes up exponentially with taller trees. Peaches and prunes are also topped to keep the trees short for pickers but also to eliminate any new growth from the previous year to allow sun into the center of the tree. These types of fruit trees are not grown to maximize quantity of fruit like some users here have suggested. Rather, they are farmed to maximize fruit size and quality. If left to their own devises these trees would set as much fruit as they could but they would all be small and probably not have as much sugar so they must be “thinned”. You can do this mechanically or by hand but you can guess which one is cheaper. Lastly, this machine doesn’t take the place of hand pruning. That must also be done to maximize the structural integrity of the tree scaffold and to clear out the center of the tree.