In all probability the callousness in tone was the point. It’s also a common device in Russian literature of the time to gloss over such brutality and hardship. It’s a bit of a trope at how commonplace suffering was made to seem in stories and other writing by Tolstoy and Dostoevsky and other contemporaries. See also: God Sees the Truth, But Waits
It would have been very unlikely that common men would have ever been taken prisoner. They'd have just been slaughtered on the battlefield, if they did not run away.
At any rate the breaking the conventions of the times is the thing that draws a mention, in the same way that a man biting a dog does.
Why don't the history teachers drop these snippets during classes?
There was no one coming to heal them. Modern medicine wasn't invented. They were spared hours of slow death.
But even if you’re right, don’t you think it deserved more than half-sentence?
For your purposes, it would be more useful to recognize when you're doing this kind of probably-wrong analysis and make the relevant qualifying announcements in your post. It's useful to do, it's even more useful when done in a self-aware fashion.
Particularly, it makes it easier for the person with the correct understanding to share it without feeling like they're pissing into the wind. My new favorite phrase is, "correct me if I'm wrong here, but..."
Read this a few times, and then return to the rest my comment...
... execution of wounded prisoners did not even warrant a whole sentence. That’s literally all Tolstoy wrote about it.
I don’t think he was callous, I think at the time it was the norm and didn’t warrant a mention except in this case the unpleasant task was delaying the transport.
^ citing from memory
^^ this is the Napoleonic war of 1812. At least 100 years later the brutality deserved mention.