My grocery is like that. Every week there are different cuts available. Prices are very good which keeps the place busy, they are constantly restocking. I can only imagine how much profit the big stores must make. They sell a lot of products that other stores don't have so I get to try a lot of stuff I haven't tried before.
Pork butt is actually not from the back end, it's above the shoulder. The butt is more marbled and tougher than shoulder. The pig uses those muscles a lot. Often they soak it in brine for a while, then smoke or BBQ it. This is where pulled pork typically comes from.
View attachment 4154361