A butcher may be employed by supermarkets, grocery stores, butcher shops and fish markets
I can see that. My father in law was a butcher at a major chain grocery store and at a butcher shop later in life.
Grocery stores often offer bakeries, butchers, delis, and fresh produce.
I am glad to see that butchers are making a come back at grocery stores. For to many years meat was precut and not as personal.
Yes, butchers formed guilds in England as far back as 1272.
Cool. I did not know that. Seems like a trade tradition that has been around since forever. It must take a lot of knowlege to be a butcher.
Yes,  Some areas expect a three-year apprenticeship
I can see why. Learning to butcher animals correctly seems easy to a layman, but I can see a lot of studying being needed to do it correctly. 
skinning (removing the hide or pelt) or scalding and dehairing (pork) seem quite difficult
Yes it does. When you think of taking a large furry animal and removing all of it to a smoothe skin seems almost impossible without damaging the hide.