They use dwarf trees so there wouldnt be much energy even if it fell to the ground but that doesnt happen either.
The shaker puts a trampoline around the tree at the top of the bare part of the trunk where the branches start.
The apples only go a foot or three and since its a dwarf there arent many branches up above to drop higher apples down on to the ones already on the trampoline dropped from below.
Ive seen something similar used on hazelnuts. Quite a while back I saw a vaccuum cleaner that picked walnuts off the ground but Im guessing theyve come up with something like the trampoline for those too.
And so far those kind of apples do not have a good flavor.