But the thing is, this farmer had a horse in their field. Not sure why, who it belonged to, how long it had been there, what the history is... etc.
All we know is what you posted which is that it was in the field one day and gone the next. The owner had it put down becuase it was "messing up the field".
A horse in a farmers field could be an issue depending on what that farmer needed that field for.
The horse could have had issues, there could have been severe arthritis for all we know, there could have been a day that he stepped in a hole and broke a leg, there could have been laminitis...
It could be that the owner couldn't find a home for it for whatever reason (the animal could have been dangerous for all we know).
You are making assumptions without any facts. It's hard to join in the pity fest without the facts.
I'm sorry if this post sounded cranky or mean.
I would have been sad too... I know I had a neighbor that had a horse laying in the field. One morning, by evening the vet put it down because it had coliced so severly which is why it was laying down. I remember thinking "what an @$$" to let that horse suffer like that. That's before my horses got loose one day and took a field trip down to her house. Not knowing where they had come from, she caught them and stuck them in the field before she went to work. I found them and took them home but stopped by that evening to thank her for catching the little monsters.
We got to talking about that bay horse that lay in her field and died. Turns out the horse was 32 years old and arthritic. She'd had it for it's entire life. It was up and fine when she left for work that morning. She had gotten a call that it was down but it was normal for it to be down for an hour, even two so she wasn't terrible concerned. When she got home she saw it was in trouble and had the vet out immediately. See how differnet the story is when you have the facts? She wasn't a jerk, she loved that horse.