Only we don't. Murders go up and down all the time. Average resident of that city doesn't really see that as "feedback". In fact, the average person is complet

Only we don't. Murders go up and down all the time. Average resident of that city doesn't really see that as "feedback". In fact, the average person is completely unaffected by that. Probably less than 0.01% of any demographic in the US is murdered in any given year in any given city. Even if the rate went up by an order of magnitude, most would barely notice. (Local TV news not withstanding.)