IMHO the entire injection procedure is to keep it “clean” and socially accepted. Very few people would be happy to see somebody being shot in the head, but seeing somebody “falling asleep” is much more “ok”. It looks less violent even though the end result is the same. Surviving a lethal injection and waking up again in that nightmare must be horrible.

The reality is that death penalty is cruel and more costly than keeping someone in prison for life, and this doesn’t even consider the human cost of executing an innocent. It just doesn’t make sense.