I suspect that a lot of that stuff goes into the void (ie disappears) for balance reasons. Otherwise what's to stop a player from killing merchants to get at stuff they shouldn't reasonably be able to afford yet? A clever player killing off a merchant to get at gear more powerful than what they should be able to get could wreck game balance, and denying you their money and good equipment for killing them discourages murderhoboing for the best equipment even if it is unrealistic
If you're just killing merchants to get stuff from them, you aren't interested in game balance. If someone other than you is forgoing game balance, it doesn't affect you.
