None of this addresses my point. You can measure dead bodies. Whether or not those get counted in the murder rate depends on social factors — are police honestly investigating themselves? are there laws that exculpate killing humans? etc

Arizona has a bill in the works that would make it legal to kill people trespassing anywhere on one’s land, intended to allow farmers with large plots of land to shoot migrants. The bill will probably get vetoed, but in a world where it passes it’s very likely that the number of killings will increase but the number of murders will drop.

Dead bodies are objective. “Murder” is not.