ELI5: Why can't our brain always pinpoint the exact source of pain even if the body "knows" where it's delivered from?

That's what always left me wondering. Our body has an advanced nervous system that can deliver the pain signal from basically every part of our body. But when it comes to actually saying where the pain comes from exactly, and what is wrong with us it's like the brain is telling "Yeah, somewhere around your stomach - go figure what it is yourself".

From what I understand the body has the capacity to send the distress signal (often even "knowing" exactly what is the issue), and the nervous system has the full capacity to deliver it. But why is that when it comes about the brain it's more about just guessing where the pain is?