On anaesthesia, and beyond into psychology
Sedative type drugs like ketamine, to use to pull someone’s dislocated shoulder or fractured hip back into line.
They don’t have any painkilling effect per se, it still hurts like **** and you’ll scream the place down. But then have no memory of it, and if you can’t remember it then there’s no harm done. The memory of something terrible is worse than the event itself.
By the same token then – executing people by humane methods, vs horrific endings. It’ll be unpleasant while it happens but after you’ll have no recollection, so what’s the problem (ignoring supposed deterrent effect on viewers, etc.)