The tops of pants or a skirt is finished with facing when
a)extra strength is required at the waistline
b) its not possible to layer the fabric
c) a stay tape cant be used in the seams
d0yu don't want the waistband to be visible from the right side.
My thinking for this is a) as the waist needs to be strong to support the weight of the skirt or pant
2 answers
I disagree with your answer. I still think it's b).
It could be either b or d. I'd be inclined to go with d. All facings are supposed to be unseen from the outside (right side) of the garment.