"Who buys A or B units or calves that are not powered."
Almost everybody. Not a reason to do it, mind you, but definitely the norm, and an esthetic choice. I have been known to power a dummy just because, usually by moving a power truck and adding tether.
("Powering a dummy" is not the same thing as "empowering a dummy", which is not a good idea.)
Steam guys like me face the issue less; our "extra units" are called "articulateds".