The difference was mostly brought about by government regulations.
In years past butchers did both the ‘kill’ and the meat cutting. Today the places that can do the whole job are regulated so much that even the specialty meat markets have to send the animals to a kill market and get back the animal dressed, ready for aging and cutting/wrapping.
The majority of Journeyman meat cutters could do the entire job if allowed by the government.
So true. Dad started out that way but by the late 50's meat plants supplied plucked chickens, beef and pork sides. The meat cutters took over from there making all the cuts in-store.
I remember my Dad's last working night (1972) when I went to pick him up. He showed me all the boxes the meat was coming in now, no more hanging sides in the walk-in freezer, just boxes. He said to me, "I'm getting out just in time, they've taken the art away".