Why do this to healthy Oaks?

 Judging from the cuts, I imagine a "tree worker" or the owners professional landscapers told the owner the trees might fall if they dont remove a few branches.

High end pruning on a Quercus agrifolia

Hired the right guy for the right price. Why does this happen when I prune large branches he asks?

Just waiting for a nice strong wind to self prune the rest.