Honestly? They have limited resources, so they have to prioritize the most important supplies. While you'd think keeping your soldiers in good shape is important, it may be less important than making sure the artillery units are getting their regular shipments of shells, stuff like that.
Especially if those "soldiers" are just some cannon fodder you recruited from a prison and sent to the front with no training. They probably won't live long, and you're not expecting them to, so it becomes a waste to spend resources maintaining them.
Also, there might be some corruption at play. Rather than explain that myself, I'll let Perun field it: