I would label it a failure if a hunting bullet doesn't expand and it is supposed to. Barnes.
Bullets that don't penetrate because they came apart on Shoulder shot is rarely a failure of the bullet, but more a failure of the hunter to pick proper placement for the bullet chosen.
If you are going to shoot a bullet designed to expand at lower velocities (Berger) why do people insist the bullet failed when they shoot shoulders at 60 yards? Or inversely, why try to use monos to shoot lungs at a greater distance and lower velocity? Again it's Shooter error.
When a bullet fails to expand on a close shot it failed. (Not including solids on dangerous game)
If you hunt areas where close shots are fairly common why would you load fragile bullets in the gun and choose to shoot at the shoulders? Why expect a solid copper bullet to expand at low velocity? Do people really think there isn't a difference?
Why not load the gun with a stout constructed bullet that shoots good enough up close to shoot wherever you want, and a long range choice available for long shots. Long shots aren't quick, and ejecting a mono to load an Accubond or Berger that's exactly what is needed in that situation will not take enough time to matter.
I surmise that blaming bullets is easier than admitting failure.