Perhaps the butcher has a magic fridge which fills with prime cuts of meat that never were part of a living animal - or if they were, they were from animals that queued up meekly for humane rendering at the hands of gentle nuns armed with nothing nastier than bowls of hemlock. And I take it your butcher would never dream of selling pheasant or venison either.

To be honest, though, I'm with you on mindless yobs who kill for the pleasure of it. People who do that are yobs and have no place in a civilised society.
If, however, they kill to put food on the table or to sell to the butcher or to control pests, then fair play, that's part of life. You may not like it - just as some people don't like morris dancers, anglers or folk who play cricket - but that's your problem, not theirs.