Lot of people - SADLY - will do this.
They are hold over from days when all animals were thought to have no feelings, no worth ... and some people do it because they don't like the owners.
I had a dog that was out on a chain for the morning - someone drove by and shot her because I was a northerner in the precious South ! Totally true ...
fortunately she was not killed, but had a bb in her forehead for the next 10 years ! Shooting a trapped animal on the owners property - so they surely feel justified to shot anything trespassing on their property. Nasty buggers must not have many friends.