Basically, they are hand harvested before they are ripe. Here is information on when they pick, followed by some on how they pick.
From University of Minnesota Extension: “The generally accepted commercial practice is to pick fruit before the onset of the respiratory climacteric. Unless your market is near your orchard and can absorb all of your fresh product, you will want to harvest your apples before they begin to ripen.
Commonly used harvest indexes are based on days from bloom, external and internal fruit color, flesh firmness, ease of separation from spurs, and starch, sugar, or acid content. No one index is a completely reliable measure of harvest readiness, but days from full bloom gives the most reliable guide.
Hand-pick fruit into bags, transfer gently into field bins, shade fruit in bins, then transport to packing sheds.”
From Dave’s Garden (emphasis is mine):“Things get more problematic if your tree is taller than ten or twelve feet. Special orchard ladders, with three legs, are expensive, and propping an extension ladder against a tree can risk a fall. In addition, the pickers need sacks hanging from their necks to hold the apples as they are gathered.”