Butt the question is?

How come a “butt,” which is two buns or cheeks is not referred to as a pair, ie., breasts?

Have you ever heard anyone say, that’s a “nice pair” of butt?  No you have not.  Butt we definitely have heard or said, that’s a nice pair of breasts.

Interestingly enough they offer a split pair of breasts in restaurants and in the grocery store, butt, not a split pair of butt?   Doesn’t this seem unfair to the derriere?

Just asking.