It is easy to explain. What happens here is perceived as fantasy, consensual or at worst a paid gig.
No matter what you may think of your desires, the percentage of you who would actually drive a nail through the palm of my hand with the intention of hanging me on a cross until I was dead is minimal. And given a chance to do it, even some of those people will shrink from the opportunity.
However, WATCHING, an animal actually get killed is another matter all together.
While killing is built into our "bios" we have layered millennia of civilization and rules (particularly) in the west that make us adverse (programmed against?) to those things. That's why hunters as a small percentage of our total population and it is difficult for our military personnel to cope with the violence they have inflicted on others.
kisses
willowfall