I mainly sub my big tree work, so it's little and medium size pruning for me.
My laborer people deal with cleanup of pruning and landscape install tasks.
In Oregon, right now, landscape maintenance workers, with about 1 year experience, get about $10 to $13 per hour.
(That's the mowing crew guys, and the work is only about 60% the labor intensity of being a ground man for trees.)
So, for the sweat and reliability needed for a stable and respectable groundman, I wouldn't expect getting and keeping one for less than $15 to $22 per hour.
The guy I sub too, brings in a worker at $25 per hour to handle limbs, ropes, gear and chipper - which I'm more than glad to pay each time we work together.
I'm bidding about 80% the cost of the higher cost services around here like Collier, or General Tree, and I still make good profit paying the $25 per hour labor cost, plus the full business wage to the other certified arborist.